﻿TRUNCILLA 15 



toothed throughout ; marsupial swelling inflated, rounded, sep- 

 arated from the shell behind by a deep sulcation, strongly 

 toothed, thinner and excavated within. Its hinder muscle 

 scars are large and circular. 



Length (male) 70, height 45. diam. 38 mm. 



Length (female) 36, height 26, diam. 22 mm. 



Ohio River drainage. 



Type locality, Ohio. 

 Unio siilcatns Lv.a, Tr. Am. Phil. Soc, III, 1830, p. 430. pi. 



viii, fig. 12.— Say, Am. Conch., No. i, 1830, pi. v. — Lea.. 



Obs., I, 1834, p. 44, pi. YiTi, fig. 12. — Chtsnu, Bib. Conch.,. 



1st sen. III, 1845, p. II. pi. I, figs. 5, 5a; Conch., 1858. pi. 



xiiT, figs. 3, 30, 36. — Reeve, Conch. Icon., XYI, 1864, pi. 



XIV, fig. 60. 

 Margarita (Unio) sulcatus Lea, Syn., 1836, p. 22 ; 1838. p. 18.. 

 Margaron (Unio) sulcatus Lea, Syn.. 1852, p. 26; 1870, p. 40., 

 Unio sulcata Deshayes, An. sans A'ert., 2d ed., VI, 1835, p. 



548. 

 Truncilla sulcata Simpson, Syn.. 1900, p. 520. 

 Unio ridibtmdus Say, New Harm. Dis., II, 1829. p. 308: 

 Am. Conch., I, 1830, pi. v. — Chenu, Bib. Conch., ist sen, 

 III, 1845, P- IL pi. I. fiR- 6. — ^KusTER, Conch. Cab. Unio, 

 1862, p. 276, pi. xciii, fig. 2. — Reeve, Conch. Icon., XVI, 

 1864, pl- XV, fig. 63. 

 Unio obliqnatus Say, Am. Conch., VI, 1834.— Kuster, Conch. 



Cab. Unio, 1862, p. 274, pi. xcii, fig. 3. 

 Unio gibbosus van perobliquus Conrad, Monog., \^L 1836, p. 



50, pi. xxvii, fig. 2. 

 Unio perobliquus Conrad, Cover of Monog., VIII, 1837. 

 Unio pectitus Conrad, Pn Ac. N. Sci. Phila., VI, 1853, p. 255; 

 Jl. Ac. N. Sci. Phila., 1854, p. 297, pi. xxvii, fig. 4- 

 The above measurements, which are taken from two fully 

 grown shells, show how much larger that of the male is. In 

 the male shells the beaks usually project farther forward than 

 they do in those of the female, in fact they often reach the ex- 

 treme anterior end as in Plcurobema dccisum. The surface 

 of the shells, male and female, is usually yellowish-green with 

 numerous rather fine but faint green, wavy rays when young- 



