﻿I^-VMPSILIS 171 



Lampsilis umdrosa (I,ea). 



*^hell somewhat obovate, subsolid, subinflated, with rather 

 low beaks, whose sculpture is very feeble ; surface nearly 

 smooth, nearly or quite rayless ; epidermis dark brown or black- 

 ish ; posterior ridge low, somewhat double, generally having a 

 darker line on the upper ridge ; left valve with two subcom- 

 pressed, somewhat ragged pseudocardinals and two remote, 

 curved, club-shaped laterals, the lower the larger ; right valve 

 with one pseudocardinal, a vestigial one above it and one club- 

 shaped lateral ; beak cavities shallow, with a few pits ; muscle 

 scars superficial, the posterior large ; nacre white or purplish. 

 Male and female shells much alike, ending behind in a slight 

 biangulation one-third of the way up from the base; both shells 

 are a little full in the posterior base, that of the female a little 

 more produced. 



Length 90, height 53, diam. 30 mm. 

 Vera Cruz, Mexico. 

 Unio umbrosus Lea, Pr. Ac. N. Sci. Phila., VIII, 1856, p. 95 ; 

 Jl. Ac. N. Sci. Phila., Ill, 1857, p. 311, pi. xxx, fig. 26; Obs., 

 VI, 1857, p. 31, pi. XXX, fig. 26. — SowERBY, Conch. Icon., 

 XVI, 1866, pi. XXXIII, fig. 170. — Fischer and Crosse, Miss. 

 Sci., Pt. 7, II, 1894, p. 587, pi. Lxvii, figs. I, la, lb. 

 Margaron (Uniu) umbrosus Lea, Syn., 1870, p. 41. 

 Lampsilis nuihrosus Simpson, Syn., 1900, p. 570. 

 Unio veracrusensis Lea, Pr. Ac. N. Sci. Phila., XII, 1868, p. 

 150; Jl. Ac. N. Sci. Phila., VI, 1869, p. 320, pi. eh, fig. 133; 

 Obs., XII, 1869, p. 80, pi. Lii, fig. 133- 

 Margaron .(Unio) veracrusensis Lea, Syn., 1870, p. 45. 

 Unio tampicoensis var. umbrosus von Martens, Biol. Cent. 

 Amer. Moll., 1900, p. 512, pi. xxxv, figs. 3-5^. 

 An abundant species, having a peculiarly rich texture. It 

 is considerable less solid and inflated than bcrlandierii, hut 

 more inflated than tampicoensis. 



The type of veracruzensis is in the Smithsonian collection, 

 and is undoubtecUy a very young umbrosa. 



