140 THE NADTILLS. 



pany with 5. striatinum and stamt'neum. Types, No. 1172. Ohio 

 River at Cannelton, Ind., collected by Mr. L. E. Daniels, Sept. 23, 

 1904 ; Elk River at Shelton, Clay co., W. Va., collected by Dr. A. 

 E. Ortmann, July 10, 1911. A. Sphaerium nlmost exactly like 

 these, and apparently identical, was collected at Joliet, 111., by Mr. 

 Jas. H. Ferriss, in 1896, (No. 1354). 



Musculium orbiculare n. sp — Mussel rather small, inequipartite, 

 nearly circular in outlines with the postero-inferior part slightly ex- 

 tended, moderately and evenly inflated ; beaks quite small, narrow, 

 little prominent, calyculate, somewhat inclined forward ; surface 

 somewhat shining, smooth, with slight, microscopic striae ; color 

 pale corneous to grayish with narrow straw colored zones along the 

 margins : shell thin, hinge slight, cardinals small, the right angu- 

 lar with the posterior part about as thick as long ; the whole tooth 

 is little projecting, inclosing a triangular excavation for the left 

 anterior ; laminae rather long, slender ; ligament and resilium rather 

 long, slight ; 



Long. 88, alt. 7.5, diam. 3.8 (100: 90 : 48). 



Hab.: III., Ind.; Athens, 111., Nason collection in the Illinois 

 State Lab. Nat. History seen in 1911. Types No. 6796. Hammond, 

 Ind., collected by Mr. L. E. Daniels, Aug. 3, 1904 (No. 4400). 



This species is markedly different from all others seen and ap- 

 pears to be distinct. It has some resemblance to M. elevatum Hald., 

 but is much smaller and slighter, less inflated, the beaks are much 

 smaller, and it differs from half grown elevatum of about the same 

 size more than it does from adults. 



There are still large numbers of Sphariida on hand, of all three 

 genera, which cannot be referred to any of the described species. 

 Yet it is precarious to establish new species on them, considering the 

 great variation of many species. On the other hand, haphazard 

 lumping would do more harm then good, and is unscientific. More 

 good material from all over the continent is desirable, and will help 

 ascertaining their real relations. Also a large number of well 

 marked varieties and subspecies, partly very interesting in several 

 respects, systematically and geographically, are on file, and will be 

 published later. 



