﻿286 CI.I-JiULA 



cavitv of beaks deep and angular; nacre salmon-colored, 

 iridescent. 



Length 52, height 28, diam. 16 mm. 



Mexico or Central America, no doubt. 

 Unio mellcns Lea, Pr. Ac. N. Sci. I'hila., XI. 1859, p. 152; Jl. 



Ac. N. Sci. Phila.. I\'. i8fe, p. 250. pi. xxxviii, fig. 129; 



Obs., Vn, i860 p. 68, pi. xxxviij, fig. 129. — Reeve:, Conch. 



Icon., XVL 1865, pi. XXI, fig. 92. 

 Margaron (Unio) melleiis Lea, Syn., 1870. p. 35. 

 Nephronaias melleus Simpson, Syn., 1900, p. 597. 



Dr. Lee states that the type of this species is in the Cun- 

 ningian cabinet, and there are no specimens in his collection. 

 Judging from the figures and his description I believe it to 

 be a female shell of some species of Nephronaias of the scam- 

 nata group. Lea remarks that it is nearest to his Unio aratus. 

 Thoitgh the typical Unio dysonii is shorter and considerably 

 wider behind than the figure Lea gives of this species. I think 

 it quite likely that the two may run together, as there are shells 

 in the National Museum collection, which are somewhat inter- 

 mediate. 



Genus GLEBULA Conrad. 1853. 



Glebiila Conrad, Pr. Ac. N. Sci. Phila.. 1853. p. 268. 



Shell solid, much inllated. short elli])tical. bluntly pointed 

 and slightly biangulate behind, with a low. posterior ridge ; 

 female shell swollen at i)ost-base ; beaks compressed, destitute 

 of sculpture ; ei)idermis brownish, cloth-like : pseudocardinals 

 divided into irregularly radiating, granular lamins. sometimes 

 to the number of a dozen or more in each valve ; hinge i)late 

 reduced to a mere rounded line behind the pseudocardinals; 

 laterals short, remote ; anterior adductor scars deep, smooth ; 

 there is in each valve only a single, large, semicircular pos- 

 terior scar with a straight edge in front ; dorsal scars numerous, 

 distinct, placed back of the pseudocardinals ; cavity of the beaks 

 not deep or compressed ; nacre dull lurid to jnirplish-brown. 



Animal with gills nearly e(|ual in size, inner slightlv the 

 larger in front, united the whole length to the abdominal sac; 

 marsupium occupying the hinder half of the outer gills ; ovi- 



