316 . THE AMERICAN MIDLAND NATURALIST 
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, subeylindrical. 
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- 
mae, 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 EF. 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 from 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.’’) 
Pl. XXV, Figs. 81 A and B. 
1900a—Ptychobranchus clintonensis Simpson, Pr. Acad. Nat. Sci. 
Phila., Pt. I, .p. 79, pl. 0... fig.ay, 1900b;. Proc.’ U.S. iat ene 
Peel, Dp. O53; 
1906—Ptychobranchus clintonense (Simpson) Scammon, Sci. Bull, 
Univ. Kans., III, p. 319. 
ANIMAL CHARACTERS:—Identical with those of the type for 
this genus as to its nutritive structures and also as to the repro- 
