340 Mr. I). Sharp's Contrlhntions to the 



The male has a narrow Ijut very deep notch on the 

 ventral plate of the 7th segment of the hind body; the 

 middle of the plate on each side of this notch has a large 

 ill-detined depression. 



Tapajos ; one $ , two $ specimens. 



Palaminus. 



The species of this genus hitherto described ai-e only 

 about twelve, and of this number only five are from 

 South America, the others inhabiting Xorth America, 

 Ceylon, and the Cape Verde Islands. Nevertheless the 

 species in South America are excessively numerous, my col- 

 lection containing about sixty species from that continent. 

 The genus is one of those where the examination and 

 description of the species in a thoroughly satistactory 

 manner is surrounded with great dillicuhies. These 

 insects are small and delicate, and the different species 

 bear the greatest resemblance inter se, and apparently in 

 some cases are found together in a gregarious manner. 

 In order to distinguish the s[)ecies a very careful examina- 

 tion of tlie sexual characters should be made, and this 

 ought to include an examination of the appendages of the 

 male intromittent organ ; these are very difierent in the 

 dilfcrent sjiccies, and in certain cases are extremely I'c- 

 markable ; bilateral asymetry is very common. The 

 external abdominal sexual characters are in some species 

 striking, while in othei'S they are scarcely present. I 

 cannot mention anv general external characters by which 

 the sex of an indixidiial may be distinguished with cer- 

 taintv, but, as a ride, it appears that an excision or notch 

 at the hind margin of the ventral ]>late of the 7th segment 

 is characteristic of the female, while a conspicuous ]iro- 

 longation of that part genei-ally indicates the individual 

 possessing it to be a male. Erichson (who in his "Genera 

 and Species " has only described four species of the 

 genus) a])i)ears to have probably fallen into error in his 

 identification of the sex of the individuals described by 

 him ; in the case of one of the species, P. variabilis, 

 he emnnerates five or six varieties, all of which will, I 

 have no d()ul)t, ])rove to be distinct species. Tweutv 

 S})ecies found by Mr. Bates are here described, as well as 

 one other captined by Dr. Trail, and, after comparing 

 them carefully with a large series of species found in the 

 neiirhbourhood of l^io de Janeiro, T fiiul not a single one 

 is common to the two localities. 



