﻿TRUNCILLA 



25 



Unto perplexus Lea, Trans. Am. Phil. Soc, l\ , 1831, p. 112, 

 pi. XXVII, fig. 42 ; Obs., I, 1834, p. 122, pi. XVII, fig. 42.— Han- 

 ley, Biv. Shells, 1843, P- 181, pi. xxii, fig. 39.— Chenu, 111. 

 Conch., 1858, pi. XVII I, figs. 5, 50, 5&. 

 Margarita (Unio) perple.viis'L-EA, vSyn. 1836, p. 17; 1838, p. 16. 

 Margaron (Unio) perplexus Lea, Syn. 1852, p. 23 ; 1870, p. 34, 

 TrunciUa perplexa Simpson, Syn., 1900, p. 522. 

 Unio gihhosus Ferussac, Guer. Mag., 1835, p. 27. — Conrad,. 

 Monog., VI, 1836, p. 50, pi. XXVII, fig. 1.— Reeve, Conch. 

 Icon., XVI, 1864, pl- XI, fig. 41, 41a, 41 &. 

 Dysnomia gibbosa Agassiz, Arch, fiir Nat, I, 1852, p. 43. 

 Unio gibbosns, Raf. v. perplexus P.^teIv, Conch. Sam.. III,. 



1890, p. 153. 

 Unio torulosus Conrad, New F. W. Shells, 1834, p. 72. 

 Unio obliquus Potiez and Michaud, Gall. Moll., 1844, p. 153,. 

 pl. EVIII, figs. 3, 4. 



Lea's species was published, according to Scudder (Bib. of 

 Isaac Lea, p. 3), in the latter part of 1831. Rafinesque pub- 

 lished a species, "TrunciUa, Unio, perplexus," in the Continua- 

 tion of a Monograph in October, 183 1, which I can not iden- 

 tify. I do not know which name appeared first, but I think it 

 best to retain the well-known and properly described name of 

 Dr. Lea. 



In this species the female shell is considerably larger tharr 

 that of the male and is produced below and behind into an 

 enormous, rounded, compressed marsupial wing, which is 

 rather thin and dark without and has a wide prismatic border. 

 The row of knobs is very variable. Sometimes these knobs 

 are ten millimeters long and much elevated, there being only 

 two or three of them in the row. In the varietv cincimiatien- 

 sis they are small and numerous while in the variety rangiana 

 they are almost or even quite wanting. 



Var. rangiana (Lea). 



S'hell more compressed than the type ; knobs on the median 

 radial ridge low or even wanting. The marsupial swelling of 

 the female shell is not quite so pronounced as it is in the type. 



