THE NAUTILUS. 81 
Unio charruana Orb. Lake Potrero, near Maldonado, Uru- 
guay. 
Unio variabilis Maton. Uruguay River at Fray Bentos. 
Unio pereformis Lea. Rio de la Plata at Colonia. The rug on 
the posterior slope mentioned by Lea as perhaps inconstant, are 
present in the specimens collected. 
MUuTELID-. 
Monocondylea Pazii Lea. Colonia, Uruguay. 
Monocondylea lentiformis Lea. Colonia, Uruguay. 
Glabaris siriones @’Orb. Rio San Carlos, Uruguay. 
Glabaris latomarginatus Lea var. felix Pils. Colonia, Uruguay. 
Glabaris rubicunda Lea. La Plata River at Colonia, Uruguay ; 
Uruguay River, Paysandu. 
Glabaris lucidus d’Orb. La Plata River at Colonia, Uruguay. 
Glabaris trapesialis var. cygneiformis Pils. Pond and a small 
ereek near Maldonado. 
Gilabaris trapesialis var. exoticus Lam. 
Anodonta exotica Lam. An.s. Vert., vi, 1819, p. 87; Delessert, 
Ree. de Coq., pl. 13, f. 1 (figure of type). 
Anodon scriptus “ Fer.” Sowb., Conch. Icon., pl. 4, f. 9 (1867). 
It is narrower than G. trapesialis, long, the anterior end very nar- 
row, angled at end of hinge-line; posterior muscle-scar quite near 
the sinus at edge of hinge ligament, connected therewith by a short 
impression. 
Rio San Carlos, Uruguay. Rather small specimens, but agreeing 
with the figure of type in Delessert’s Recueil. 
Glabaris Forbesianus Lea. Rio de la Plata, Colonia, Uruguay. 
Lea’s figure was from a deformed shell, and the specimens would 
hardly have been recognized as Forbesianus had it not been for the 
kindness of Mr. Simpson, who compared with the types. 
ISAAC LEA DEPARTMENT. 
[Condueted in the interest of the Isaac Lea Conchological Chapter of the Agassiz Associa- 
tion by its General Secretary, Mrs. M. Burton Williamson. ] 
Members of our Chapter will please bear in mind the fact that 
the annual reports are due in December. We anticipate some fine 
papers this year as our members have been enthusiastic in their 
study of shells. 
