﻿194 I.AMPSII.IS 



which often fade out at the border of the shell; the wm^', m 

 fine specimens having- a broad, faint, darker ray, whose base 

 lies along the dorsal line; epidermis thin, cloth-like; left valve 

 with an elongate pseudocardinal, sometimes there are vestiges 

 of others, and two straig-ht, delicate laterals ; right valve with 

 two lamellar pseudocardinals and one lateral ; beak cavities very 

 shallow with a few pits; muscle scars scarcely discernable ; 

 nacre brilliant, shining with a metallic luster, yellowish or 

 purplish. I have examined a number of shells and in a few 

 there is a slight fullness near the posterior base not seen in 

 others, and these may be females. 



Length 58, height, with wing, 45, without the wing 26, diam. 

 10 mm. 



Guatemala ; Monte Cristo, Tabasco, Mexico. 

 Unio dclphinitliis MoRKi.i-rr, Test. Noviss., I, 1849. ]). 31. — 



Hanley, Biv. Shells, 1856, p. 381, pi. xxiii, fig. 60. — Sow- 



ERBY, Conch. Icon., XVI, 1866, pi. xliii, fig. 237. — Fischer 



and Crosse, Miss. Sci., II, 1894, p. 557, pi. lxiii, figs. 2, 



2a, 2b. 

 Margaron (Unio) delphinuhis Lea, Syn., 1870, p. 28. 

 Lampsilis delphinulus Simpson. Syn., icxx), p. 576. 



A striking and delicate shell. The front line of the great 

 dorsal wing rises at an angle of about 60° ; its posterior line 

 form.s a perfect ogee from the summit to the posterior point. 



Lampsims i,argiij.ierti (Philippi). 



"^'ucatan. 

 Unio largillierti Phiijjppi, Zeits. fiir Mai., IV, 1847, P- 94- — 



VON Martens, Biol. Cent. Amer., Moll., 1900, p. 521. 

 Lampsilis largillierti Simpson, Syn., 1900, p. 577. 



Unfigured and unknown to me. From the description, which 

 is not accessible to me at the present time, I should tliink that 

 it probably belonged here, von Martens, (1. c"), suggests that 

 it may be the same as paludosa Morelet. 



