570 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



(Group ^»t" JAiiitp.silis iimhrositfi.) 



Shell solid, inflated, sliort-e]li])tical, covered with a shining, rather 

 smooth brownish epidermis which often has microscopic, radiating 

 folds; beak sculpture excessively faint, being the merest hint at a 

 double loop; anterior end of the shell suddenly thickened, that of 

 the male scarcely differing from the female; hinge teetli well devel- 

 oped; pseudocardinals strong; laterals large, straight, and club- 

 shaped, nacre whitish or purplish. Animal with the inner gills united 

 to the abdominal sac; branchi;Te large; marsupium occupying the whole 

 outer gills posteriorly, not projecting much below; palpi large, consid- 

 erably united behind. 



tLAMPSILIS UMBROSUS Lea. 



** Unio umbrosus Lea, Pr. Ac. N. Sci. Phila , VIII, 1856, p. 95; *J1. Ac. N. Sci. 

 Phila., Ill, 1857,p.311,pl.xxx,fig.26; Obs.,VI, 1857,p. 31, pi. xxx,fig. 26.— 

 'SoWERBY, Conch. Icou., XVI, 1866, pi. xxxiii, fig. 170.— *B. H. WriCxHT, 

 Check List, 1888.— * P.etel, Conch. Sam., Ill, 1890, p. 171.— * Fischer and 

 Crosse, Miss. Sci., Pt. 7, II, 1894, p. 587, pi. lxvii, figs. 1, la, lb. 



* Margaron {Unio) umbrosus Lea, Syn., 1870, p. 41. 



t Unio veracruzensis Lea, Pr. Ac. N. Sci. Phila., XII, 1868, p. 150; *J1. Ac. N. Sci. 



Phila., VI, 1869, p. 320, pi. Lii, fig. 133; ^^ Obs., XII, 1869, p. 80, pi. lii, fig. 



133. — *B. H. Wright, Check List, 1888.— Tischer and Crosse, Miss. Sci., 



Pt. 7, II, 1894, p. 605. 

 *Margaron ( Unio) veraGTuzensis Lea, Syn., 1870, p..45/^ 



Vera Cruz, Mexico. 



tLAMPSILIS BERLANDIERI Lea.^ 



* Unio berlandierii Lea, Pr. Ac. Phila., I, 1857, p. 101; Ml. Ac. N. Sci. Phila., IV, 



1860, p. 369, pi. Lxv, tig. 194; Obs. VIII, 1860, p. 51, pi. lxv, fig. 194.— 

 "Eeeve, Conch. Icon., XVI, 1865, pi. xxiii, fig. 108.— *B. H. Wright, Check 

 List, 18>^8.— * P.ETEL, Conch. Sam. Ill, 1890, p. 146.—* Pilsbrv, Naut. V, 1891, 

 p. 76.—" Fischer and Crossk, Miss. Sci., Pt. 7, II, 1894, p. 584. 



* Margaron ( Unio) berlandierii Lea, Syn., 1870, ]). 36. 



Northeastern Mexico; southwestern Texas. 



tLAMPSILIS TAMPECOENSIS Lea. 



* Unio tampecoensis Lea, Tr. Am. Phil. Soc.,VI, 1838, p. 24, pi. vii, fig. 18 ; * Obs., II, 



1838, p. 24, pi. VII, fig. 18.— ^Troschel, Arch. Inr Natnrg., V, 1839, Pt. 2, p. 

 235.— ^Hanley, Test. Moll., 1842, p. 188; * Biv. Shells, 1843, p. 188.— 'Catlow 

 and Eeeve, Conch. Nom., 1845, p. 64.— * Conrad, Pr. Ac. N. Sci. Phila., VI, 



1 The type of veracruzensis is in the Smithsonian collection, and is undoubtedly a 

 very young umbrosus. 



-This species is extremely close to L. tampecoensis, and at one time I believed the 

 two to be mere forms of the same thing. The present species is typically heavier 

 and more inflated, as well as lighter colored, and has higher beaks than the latter. 

 According to Hon. J. D. Mitchell, of Victoria, Texas, who has carefully studied these 

 forms when living, berlaudieri is more active, and while spawning it only buries 

 itself sufficiently to lie steady and give the post ventral portion an elevation, while 

 tampecoensiH is sedentary in its habits, and buries itself entirely, excepting the 

 extreme posterior point. Letter of Septemb. r 25, 1895. 



