ORDER ABRANCHIA. 
33 
Blainville thinks that the difference arises from its having been 
confounded with a nearly-allied species, the Black Leech , 
which he makes the type of a genus that he calls Pseudob- 
DELLA, and of which the jaws are merely folds of the skin 
without any teeth. I believe this fact would deserve a fresh 
investigation. Both species devour Lumbrici with avidity. 
Bdella, have but eight eyes, and the mouth is com- 
pletely destitute of teeth. M. Moquin-Tandon changes this 
name into Limnatis. 
There is one in the Nile, Bd. Nilotica , Egg. Annel. pi. v. 
f. 4. 
NepheliS, Sav ., have also but eight eyes, and their mouth 
internally has but three folds of the skin. M. de Blainville 
names them ERPOBDELLiE, and M. Oken Helluo. Such 
are Hir . vulgaris , L , or H. octoculata , Bergm., Mem. de 
Stockh. 1767, pi. vi. f. 5 — 8 ; N. atomaria , Caren. L. C. pi. 
xii. See also pi. vi. of M. Moquin-Tandon. 
There are many small species in our waters, among wdiicli 
vve distinguish Trochetia ^JDutroclietj Geobdella, Blainv.^ 
which differ only by an enlargement at the seat of the genital 
organs. 
We have one species of them, which frequently comes to 
land to pursue the lumbrici, Geobdella trochetii , Blainv. 
Diet, des Sc. Nat. Hirud. pi. iv. f. 6. 
M. Moquin Tandon, under the name of Aula STOMA, de- 
scribes a subgenus whose mouth is also furnished with nothing 
but longitudinal folds tolerably numerous, Aulast . nigrescens , 
Moq. Tand. pL vi. f. 4. 
After Nephelis are placed the Branchiobdella, of M. 
Odier, remarkable for jaws, two in number, and the absence 
of eyes. 
One species is known, which lives on the gills of the astaci. 
Branchiobdella astaci , Od. Mem. de la Soc. d’Hist. Nat. de 
Paris, tom. i. pi. iv. 
vol. xm. 
i) 
