﻿334 I'TYCIIOimANCHUS 



with two low. solid, rather small ])scu(locar(linals and two 

 club-shaped laterals, the hiiiL^e plate bein^ ol>li(]uely truncate 

 behind : ri^ht valve with one ])seudocardinal and vestigial ones 

 in front of and behind it. with one strong lateral, which some- 

 times has vestigial ones above and below it ; beak cavities very 

 shallow, with faint dorsal scars ; muscle scars well impressed, 

 smooth ; nacre silvery-white, with one or two oblique shallow 

 grooves. 



IvCngth TOO. height fx), diam. 33 mm. 



Length ck>. height 55. diam. 25 mm. 



Length 90, height 45, diam. 25 mm. 



Ohio, Tennessee, and Cumberland River systems ; Lower 

 Peninsula of Michigan; Kansas: .Arkansas; Indian Territory; 

 Louisiana. It is quite probable that some of the specimens 

 reported from the southwestern part of the range belong to 

 the next species. 



Type locality, IMuskingum River. (). 

 Unio phaseohis Hildretii, Am. Jl. Sci., XI \', 1828, p. 28^^,. — 



Say, Am. Conch., No. Ill, 1830, pi. xxii. — Hanley, Biv. 



Shells. 1843, P- 207, pi. XX, fig. 50. — Chenu, Bib. Conch., 



ist ser.. Ill, 1845. P- 3i> P^- i^^ ^S^- ^"6. — Sowerby, Conch. 



Icon., XVI, 1868, pi. Lxxiii, fig. 378. 

 Margarita fUnio) phascolus Lea, Syn., 1836, p. 38; 1838, p. 25. 

 Margaron (Unio) phascolus Lea, Syn., 1852, p. 38; 1870. p. 61. 

 PtychohrancJius phascolus Simpsox, Syn.. 1900, p. 613. 

 Unio planulatus Lea, Tr. Am. Phil. Soc, III, 1830. p. 431. pi. 



IX, fig. 13; Obs., I, 1834, p. 45, pi. IX, fig. 13. — Chexu, 111. 



Conch., 1858. pi. XIII. figs. T. la, \h \ Manual. 1850, II, p. 



^Z7^ % 659- 

 Unio planulata 1^i:siiayes, An. sans \'ert.. 3d ed.. II. 1839. p. 



672. 

 Unio fasciolaris Conrad. New F. W. Shells. 1834. p. 6<).— 



KusTER. Conch. Cab., 1861. p. 172, pi. i.iv. figs. 1-4. 

 Unio compressissimus Lea, Pr. Am. Phil. Soc, IV, 184^, p. 



163 ; Tr. Am. Phil. Soc, X, 1848, p. 81. pi. vm. fig. 3^ : <^1^« ■ 



TV, 1848. p. 81. pi. viTi, fig. 23. 

 Margaron (Unio) compressissimus Lea. Syn., 1852, p. 24: 



1870, p. 37. 



