76 
Orinoco, one of the most central positions in South America. They 
are most abundant in the smaller streams, and feed on minute aqua- 
tic insects. None of them, except the common Gymnotus, have 
any electrical properties. They are all eaten, though, owing to the 
number of forked or branched bones in every part of their bodies, 
they are not much esteemed. . 
The situation of the vent in these fishes is very peculiar, the in- 
testine passing forwards from the stomach, instead of backwards, as is 
usually the case, so that they have the anus situated under the throat; 
in one of the long-snouted species it is actually considerably in front 
of the eyes, a peculiarity which I believe does not occur in any other 
vertebrated animal. 
This fish, too, is remarkable for the very singular manner in which 
it is said to feed. It is asserted that it lives principally on ants and 
white ants, which it obtains by laying its tail out upon land. The 
ants, attracted by its mucous covering, crawl thickly upon it, when 
the fish dives down and leaves the ants struggling upon the sur- 
face of the water, where it is enabled to eat them at its leisure. The 
Indians assert that, when fishing at night, they often see this take 
lace. 
s To give some idea of the distribution of fishes in the rivers of 
South America, I may mention, that of 205 species which I found in 
the Rio Negro,— 
43 were spinous-finned fishes, principally Percide and Labride ; 
54 were Siluride ; 
80 were Salmonide ; 
24 were other soft-finned fishes, of the families Hsocide, Anguillide 
and Cyprinide ; and 
4 were Ray fish (cartilaginous fishes). 
2. Descriptions p ANCYLES NOUVEAUX, DE LA COLLECTION 
DE M. CumMING, PRECEDEE D'UNE COURTE NOTICE SUR 
LE GENRE ANCYLUS, ET D’UN CATALOGUE COMPLET DES 
ESPECES QUI LE COMPOSENT. Par M. J. R. BourGguienat. 
(Mollusca, Pl. XXV.) 
M. Cuming, sur la recommandation du savant conchyliologue 
frangais, M. Deshayes, ayant bien voulu nous communiquer sa col- 
lection d’ dncyles, nous nous sommes empressés de l’examiner ; et 
comme nous y avons reconnus plusieurs espéces inconnues jusqu’d ce 
jour, nous croyons devoir en donner les descriptions. 
Nous les ferons précéder de quelques courtes notes sur le genre 
méme auquel ces coquilles nouvelles appartiennent, et d’une liste de 
toutes les espéces jusqu’ici connues. 
Mais tout d’abord, n’oublions pas de remercier M. Cuming de la 
communication si bienveillante qu’il a bien voulu nous faire; l’ex- 
tréme bonne grace qu’il y a mis ne nous a point surpris; nous n’at- 
tendions pas moins de lui, tous les conchyliologues savent qu’il joint 
