﻿350 STROPHITUS 



A)iodoii niiditlata Cati.ow and Reicve, Conch. Nom., 1845, p. 



68. 

 Alasmodonta uiidnlata C. P>. Adams, 'riiom])son"s Hist. Yt., 



1842, p. 165. 

 Margaron (Anodonia) iiitdiilata Ij:a. Syn.. 1852. p. 49; 1870, 



P- 79- 

 Strof^hitiis iiiidnlatiis v'^Ti mi-son, Shells of X. Ens^.. 1851. p. 15. 



— Simpson, Syn.. 1900. p. 618. 

 Anodonta pcnnsylvanica L<amakck. An. sans ^'ert.. \'I. 1819, 



p. 86. — Dei.esskrt, Rec. Coq. Lam., 1841, pi. xiii, figs. 4a, 



46. — Chenu, 111. Conch.. 1858, pi. iii, figs. 5, 50. 

 Anodon papyraceus Anthony, Am. Jl. Conch., T, 1865, p. 161, 



pi. XV, fig. 2. — SowERBY, Conch. Icon.. X\'II, 1867, P'- ^iv, 



fig. 46. 

 Anodonta papyracca 15. H. Wright, Check List, 1888. 

 Margaron (Anodonta) papyracea Lea, Syn., 1870, p. 81. 



Var. quadriplicatus (Sowerby). 



Shell rather more elongated than the type, more distinctly 

 and widely biangulate behind and usually quite plainly rayed. 



Type locality, Potomac River. 

 Anodon quadriplicatus Sowekhy, Conch. Icon., XVII, 1867, 



pi. XXVIII, fig. no. 



Some specimens of this variety arc so distinct that they 

 almost seem worthy of specific rank, being quite elongated, 

 strongly and widely biangulate behind, and decidedly rayed. 

 But there is a great variety of intermediate material. Say's 

 figure of A. undulata represents a young or extremely small 

 shell, but I feel no hesitation in identifying it with the rather 

 common Strophitus found in the Atlantic system of drainage. 

 It is thinner than the usual manifestation of cdcntidiis, gener- 

 all\' smaller, more rhoml)oid, aiid having a siiioky-broicii epi- 

 dermis typically. The nacre is usually bluish, especially around 

 the border of the shell. vSo far as I know the .S". undidatus and 

 its variety are confined to the Atlantic and St. Lawrence drain- 

 age systems, while 5*. edentulus belongs in this territory and 

 a large part of the Mississij^pi area. 



