340 ^h: D. Sliarp's Cuiitrihntlons to the 



The male luis a nari'ow but very dec]) notcli on tlie 

 ventral i)late of the 7th segment of the hind body ; tlie 

 middle of the plate on each side of this notch has a larj^e 

 ill-defined depression. 



Tapajos; one ^, two $ specimens. 



Palaminus. 



The species of this genus hitherto described are only 

 about twelve, and of this number only five are from 

 South America, the others inhabiting North America, 

 Ceylon, and the Cape Verde Islands. Nevertheless the 

 species in South America are excessively numei'ous, 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 satisfactory 

 manner is surrounded with great ditticulties. These 

 insects are small and delicate, and the different species 

 bear the greatest resemblance inter se, and apparently in 

 some cases ai-e found together in a gregarious manner. 

 In order to distinguish the species a very careful examina- 

 tion of the sexual characters should be made, and this 

 ought to include an examination of the aj)pendages of the 

 male intromittent organ ; these are very different in the 

 different species, and in certain cases are extremely re- 

 markable ; bilateral asymetry is very common. The 

 external abdominal sexiuil characters are in some species 

 striking, Avhile in others they are scarcely present. I 

 cannot mention any general external characters by Avhich 

 the sex of an individual may be distinguished with cer- 

 tainty, but, as a rule, it appears that an excision or notch 

 at the hind margin of the ventral plate of the 7tli segment 

 is characteristic of the female, while a conspicuous ])ro- 

 longation of that part generally 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])pears 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 doubt, prove to be distinct species. Twenty 

 species found by Mr. Bates are here described, as well as 

 one other captured by Dr. Ti'ail, and, after comparing 

 them carefully with a large series of species found in the 

 neighbourhood of Kio de tJanciro, I find not a single one 

 is common to the two localities. 



