A strange kind of wood-cricket is found in this neighbourhood: the males produce a very loud and not unmusical noise by rubbing together the overlapping edges of their wing-cases. ‘The notes are certainly the loudest and most extraordinary that I ever heard produced by an orthopterous insect. ‘The natives call it the Tananda, in allusion to its music, which is a sharp, resonant stridulation resembling the

More than three-fourths of the individuals ‘in these congregations of butterflies consisted of a pale sulphur-coloured species, C. Statira: two yellow kinds, C. Eubule and C. Trite, and one orange-coloured, C. Argante, were less numerous. A few of a much larger species (C. Leachiana), sulphur-coloured, with orange tips to the wings, now and then occurred amidst the masses.

syllables ta-na-na, ta-na-nd, succeeding each other with little intermission, It seems to be rare in theneighbourhood. When the natives capture one, they keep it in a wicker-work cage for the sake of hearing it sing. A friend of mine kept one six days. It was lively only for two or three, and then its loud note could be heard from one end of the village to the other. When it died, he gave me the specimen, the only one I was able to procure. It is a member of the family Locustide, a group intermediate between the Crickets (Achetidze) and the Grasshoppers (Acridiidz).. The total length of the body is two inches and a quarter; when the wings are closed, the insect has an inflated vesicular or bladder-like shape, owing to the great convexity of the thin,

(Ger Lf

Musical Cricket (Chloroccelus Tanana).

a, b, Lobes of wing-cases transformed into a musical instrument.

but firm, parchmenty wing-cases, and the colour is wholly pale-green. The instrument by which the Tanana produces its music is curiously contrived out of the ordinary nervures of the wing-cases. In each wing-case the inner edge, near its origin, has a horny expansion or lobe; on one wing (4) this lobe has sharp raised margins; on the other (a) the strong nervure which traverses the lobe on the other side is crossed by a number of fine sharp furrows like those ofa file. When the insect rapidly moves its wings, the file of the one lobe is scraped sharply across the horny margin of the other, thus producing the sounds; the parchmenty wing-cases and the hollow drum-like space

which they enclose assisting to give resonance to the tones. The projecting portions of both wing-cases are traversed by a similar strong nervure, but this is scored like a file only in one of them, in the other remaining perfectly smooth. Other species of the family to which the Tanana belongs have similar stridulating organs, but in none are these so highly developed as in this insect; they exist always in the males only, the other sex having the edges of the wing-cases quite straight and simple. ‘The mode of producing the sounds, and their object, have been investigated by several authors with regard to certain European species. They are the call-notes of the males. In the common field-cricket of Europe the male has been observed to place itself, in the evening, at the entrance of its burrow, and stridulate until a female approaches, when the louder notes are succeeded by a more subdued tone, whilst the successful musician caresses with his antennze the mate he has won. Any one, who will take the trouble, may observe a similar proceeding in the common house-cricket. The nature and object of this insect music are more uniform than the structure and situation of the instrument by which it is produced. This differs in each of the three allied families above mentioned. In the crickets the wing-cases are symmetrical; both have straight edges and sharply-scored nervures adapted to produce the stridulation. A distinct portion of their edges is not, therefore, set apart for the elaboration of a sound-producing instrument. In this family the wing-cases lie flat on the back of the insect, and overlap each other for a considerable portion of their extent. In the Locustide the same members have a sloping position on each side of the body, and do not overlap, except to a small extent near their bases; it is out of this smail portion that the stridulating organ is contrived. Greater resonance is given in most species by a thin transparent plate, covered by a membrane, in the centre of the overlapping lobes. In the Grasshoppers (Acridiide) the wing-cases meet in a straight suture, and the friction of portions of their edges is no longer possible. But Nature exhibits the same fertility of resource here as elsewhere; and, in contriving other methods of supplying the males with an instrument for the production of call-notes, indicates the great importance which she attaches to this function. The music in the males of the Acridiidz is produced by the scraping of the long hind thighs against the horny nervures of the outer edges of the wing-cases; a drum-shaped organ placed in a cavity near the insertion of the thighs being adapted to give resonance to the tones.

I obtained very few birds at Obydos. ‘There was no scarcity of birds, but they were mostly common Cayenne species. In early morning the woods near my house were quite animated with their songs—an unusual thing in this country. I heard here for the first time the pleasing wild notes of the Carashué, a species of thrush, probably the Mimus lividus of ornithologists. I found it afterwards to be a common bird in the scattered woods of the campo district near Santarem. It is a much smaller and plainer-coloured bird than our thrush, and _ its song is not so loud, varied, or so long sustained; but the tone is of a sweet and plaintive quality, which harmonises well with the wild and silent woodlands, where alone it is heard, in the mornings and evenings

of sultry tropical days. In course of time the song of this humble thrush stirred up pleasing associations in my mind, in the same way as those of its more highly endowed sisters formerly did at home. There are several allied species in Brazil; in the southern provinces they are called Sabiahs. The Brazilians are not insensible to the charms of this their best songster, for I often heard some pretty verses in praise of the Sabiah, sung by young people to the accompaniment of the guitar I found several times the nest of the Carashué, which is built of dried grass and slender twigs, and lined with mud; the eggs are coloured and spotted like those of our blackbird, but they are considerably smaller. I was much pleased with a brilliant little red-headed manikin which I shot here (Pipra cornuta). There were three males seated on a low branch, and hopping slowly backwards and forwards, near to one another, as though engaged in a kind of dance. In the pleasant airy woods surrounding the sandy shores of the pool behind the town, the yellow-bellied Trogon (T. viridis) was very common. Its back is of a brilliant metallic-green colour, and the breast steel blue. The natives call it the Suruqua do Ygapd, or Trogon of the flooded lands, in contradistinction to the various red-breasted species, which are named Suruquds da terra firma. I often saw small companies of half a dozen individuals, quietly seated on the lower branches of trees. They remained almost motionless, for an hour or two at a time, simply moving their heads, on the watch for passing insects; or, as seemed more generally to be the case, scanning the neighbouring trees for fruit; which they darted off now and then, at long intervals, to secure, returning always to the same perch.

The species of mammals, birds, and insects found at Obydos are, to a great extent, the same as those inhabiting the well-explored tract of country lying along the seacoast of Guiana. No other locality visited in the Amazons region supplied, among its productions, so large a proportion of Guiana forms. The four monkeys already mentioned all recur at Cayenne. A general resemblance of the species to those of Guiana is one of the principal features in the zoology of the Amazons valley; but in the low lands a great number exist only in the form of strongly modified local varieties; indeed, many of them are so much transformed that they pass for distinct species; and so they really are according to the received definitions of species. In the somewhat drier district of Obydos, the forms are more constant to their Guiana types. We seem to obtain here a glimpse of the manufacture of new species in nature. The way in which these modifications occur merits a few remarks. I will therefore give an account of one very instructive case which presented itself in this neighbourhood.

The case was furnished by certain kinds of handsome butterflies belonging to the genus Heliconius,* a group peculiar to Tropical

This genus has long been known under the name of Heliconia: a most inconvenient term, as a botanical genus bears the same name. An author has lately proposed to revert to the masculine termination of the words, as first employed by Linnzus (Felder, in the Wiener Entomologische Monatschrift, March 1862), and, as I think the correction a good one, I adopt it.

America, abounding in individuals everywhere in the shades of its luxuriant forests, and presenting clusters of varieties and closely allied species, as well as many distinct, better marked forms. The closely allied species and varieties are a great puzzle to classifiers; in fact, the group is one of those wherein great changes seem to be now going on.

Heliconius Melpomene.

A conspicuous member of the group is the H. Melpomene of Linnzeus. This elegant form is found throughout Guiana, Venezuela, and some parts of New Granada. It is very common at Obydos, and reappears on the south side of the river in the dry forests behind Santarem, at the mouth of the Tapajos. In all other parts of the Amazons valley, east-

Heliconius Thelxiope.

ward to Para and westward to Peru, it is entirely absent. This absence at first appeared to me very strange; for the local conditions of these regions did not appear so strongly contrasted as to check, in this abrupt manner, the range of so prolific a species; especially as at Obydos and Santarem it occurred in moist woods close to the edge of the river. Another and nearly allied species, however, takes its place in the forest plains: namely, the H. Thelxiope of Hiibner. It is ot the same size

and shape as its sister kind, but differs very strikingly in colours: H. Melpomene being simply black with a large crimson spot on its wings, whilst H. Thelxiope has these beautifully rayed with black and crimson, and is further adorned with a number of bright yellow spots. Both have the same habits. H. Melpomene ornaments the sandy alleys in the forests of Obydos, floating lazily in great numbers over the lower trees; whilst H. Thelxiope, in a similar manner and in equal numbers, adorns the moister forests which constitute its domain. No one who has studied the group has doubted for a moment that the two are perfectly and originally distinct species, like the hare and rabbit, for instance, or any other two allied species of one and the same genus. The following facts, however, led me to conclude that the one is simply a modification of the other. There are, as might be supposed, districts of forest intermediate in character between the drier areas of Obydos, etc., and the moister tracts which compose the rest of the immense river valley. At two places in these intermediate districts, namely Serpa, 180 miles west of Obydos, on the same side of the river, and Aveyros, on the lower Tapajos, most of the individuals of these Heliconi which occurred were transition forms between the two species. Already, at Obydos, H. Melpomene showed some slight variation amongst its individuals in the direction of H. Thelxiope, but not anything nearly approaching it. It might be said that these transition forms were hybrids, produced by the intercrossing of two originally distinct species: but the two come in contact in several places where these intermediate examples are unknown, and I never observed them to pair with each other. Besides which, many of them occur also on the coast of Guiana, where H. Thelxiope has never been found. These hybrid-looking specimens are connected together by so complete a chain of gradations that it is difficult to separate them even into varieties, and they are incomparably more rare than the two extreme forms. They link together gradually the wide interval between the two species. One is driven to conclude, from these facts, that the two were originally one and the same: the mode in which they occur and their relative geographical positions being in favour of the supposition that H. Thelxiope has been derived from H. Melpomene. Both are nevertheless good and true species in all the essential characters of species; for, as already observed, they do not pair together when existing side by side, nor is there any appearance of reversion to an original common form under the same circumstances.

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