Fislies of the Genus Arges. /iSo 



■Nvitli tliose published of ^. homodon, Guentheri, and Boulenyeri 

 and with tliat of FIn;ii])oldt's Pimelodi/s ci/clopvm, will show 

 with sufficient clearness that the hrst-naraed species differs 

 very considerahly from the others in the structure of the 

 adipose fin and that there cannot be the least doubt that 

 A. Elijemnanni is not identical with Humboldt's fish. 

 A. homodon is most certainly not a male example of 

 A. Guentheri, from males of which species it differs not only 

 in the much more anterior insertion of the ventrals, l)ut 

 also in the much more posterior position of the vent, the 

 more posterior situation of the spine of the adipose fin, and 

 in other characters also. 



The suggestion that the Peruvian species, viz. A. longifiUs, 

 sabaloj Taczanoivskil, peruanus, and Siinonsii, in reality re- 

 present only one or two, cannot be entertained. A. peruanus 

 and A. Sinionsii present so peculiar a dentition that I was 

 in doubt as to whether they ought not to constitute a 

 distinct genus, and as the latter species is represented by 

 larger specimens (5 in number) in Avhich the barbel is nearly 

 twice as long as in the smaller examples of A. peruanus, 

 there can be no question as to the validity of these two 

 species. The other three differ from each other so widely 

 that there can be no excuse for confounding them, and 

 1 need only refer to my synopsis of the species and to tlie 

 published descriptions and figures. 



In the whole genus the only point as to which I entertain 

 some doubt is as to whether A. Eigenmanni is distinct from 

 A. Jrhymperi. The latter is based on a single specimen and 

 it is proi)able that the somewhat shorter ventral and more 

 posterior vent may be due only to individual variation. 

 A. Vaillanti, based on three specimens (not one only as stated 

 by Messrs. Evermann and Kendall) with a much shorter 

 caudal peduncle (6-6^ in the length of the fish, instead of 

 4|-5 as in A. Eigenmanni) , is certainly distinct. 



Some other points in Messrs. Evermann and Kendall's 

 paper call for comment. They consider that the elongate 

 anal papilla of the male fish represents the first anal ray of 

 the female. This view is completely negatived by the 

 structure of the papilla, by the fact that it is constantly 

 present in the female, although smaller, and by the obvious 

 homology between the first subspinous ray of the anal fin in 

 the two sexes. jNIoreover, difference in the number of anal 

 rays is either individual or specific, not sexual. 



The American authors prefer the generic name Cyclopium 

 to Arges, whatever the objections which may be urged 

 against it on the ground of its formation. This, of course, is 



