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, while the successful musician caresses with his antennae the mate he has won.Anyone 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 Locustidae 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 small 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 (Acridiidae) 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 Acridiidae 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 Carashue, 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 Ioften 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 Carashue, 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 mannikin, 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 Ygapo, or Trogon of the flooded lands, in contradistinction to the red-breasted species, which are named Surtiquas 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.
