I 28 THE NAIADES OF MISSOURI 



Animal Characters: — Branchial opening with papillae; 

 anal separated from supra-anal by short mantle connection but never 

 lacking; inner laminae of inner gills, more or less free from vis- 

 ceral mass; palpi very small, connected about one-fourth of 

 their length; color of soft parts mostly whitish with mantle edge 

 black along the siphonal openings; marsupium occupying whole 

 outer gill with a number of folds; ventral edge, when gravid, 

 presenting a beaded appearance; glochidia medium in , size, 

 subovate; conglutinates white, solid, subcylindrical. 



Shell Characters: — Shell subelliptic rather elongate, arched 

 dorsad, disk smooth; beaks low, sculpturing indistinct, finely 

 concentric, later bars, however, somewhat double-looped; epi- 

 dermis yellowish to olivaceous, painted with capillary-like rays 

 forming interrupted squarish spots; hinge teeth well formed, 

 branchial impression of female shell very distinct, nacre white 

 to pearl blue. 



Miscellaneous Remarks: — This most primitive genus of 

 Lampsilinae, like those of Anodontinae and some genera of Union- 

 inae, uses the whole outer gill as a marsupium but shows modern 

 character in the special structure of folding. Ellipsaria is only 

 represented in this State (and perhaps only for the whole South- 

 west) by E. clintonensis Simpson. Since the shell of this species 

 is about the same form as that of dilatata (Raf.) it is often confused 

 with this species of Elliptio /rom which is widely separated by a 

 sub-family. The real test of distinction between these two species 

 is concerning the marsupial characters; hence we see here an 

 instance of shell characters as a poor guide for discrimination 

 even for species of very distant relation. 



Ellipsaria clintonensis (Simpson.) 



("Kidney Shell.") 



PI. XXV, Figs. 81 A and B. 



1900a — Ptychobranchus clintonensis Simpson, Pr. Acad. Nat. Sci. 



Phila., Ft. r, p. 79, pi. v., fig. 3; 1900b, Proc. U. S. Nat. IVIus., 



XXII, p. 613. 

 1906 — Ptychobranchus cluitonense (Simpson) vScammon, vSci. Bull, 



Univ. Kans., Ill, p. 319. 



Animal Characters: — Identical with those of the type for 

 this genus as to its nutritive structures and also as to the repro- 



