“ANAIDES OF MISSOURI i4i 
rulae, medium in size, greatly inflated, characteristically sulcated 
post-ventrad; dorsal ridge prominent, the slopes coarsely cos- 
tated; post-umbonal ridge prominent and profusely tubercled; 
radial furrow deep and wide, in front of which another row of 
rather scattered tubercles extend from the beaks post-ventrad 
across the disk; epidermis dark yellowish. 
INTERNAL STRUCTURES :—Identical with those of Q. quadrula. 
Sex Length Height Diameter Locality 
Sie63 xiig0 Xx! agimm (Miss., R. Hannibal, Mo.) 
Q 44 x 39 x 18 ” ( ” ” ” ”? Vie 
Cre 2 Sue UXaur SG pene: elu ae (102 R., St. Joseph, Mo.) 
Citas GaN ie <M, tie (Osage R., Schell City, Mo.) 
It may be that the juvenile shell measurement of the last 
two above is only that of Q. quadrula since all juveniles of the 
latter possess the characteristic sulcation at the post-ventral 
portion of the shell as well as the profuse costation on the slopes 
of the post-dorsal ridge; hence, the inferrence the author would 
draw in asserting that Q. fragosa may be an occasional instance 
of an overgrown shell of Q. quadrula. 
MISCELLANEOUS REMARKS:—This type of Conrad is of rare 
occurrence in this State, the Mississippi being the only place 
where anything like its type may be found with any degree of 
assurance. Abnormal forms of fragosa are seen occasionally in 
the headwaters of the Osage. Simpson is not certain about the 
distribution of fragosa outside of the Ohio and Tennessee—Cum- 
berland systems. It is mainly distinguished from typical Q. quad- 
rula by being more squarely quadrate, more inflated and the 
upcurved tubercular costae on the rounded post-dorsal ridge 
being more pronounced. It differs chiefly from aspera, (the small 
Q. quadrula form of the Osage) in not being biangulated pos- 
‘teriorly. It has been found to belong to the short period breeders. 
Quadrula aspera (Lea). 
(‘Little Rough Shell.’’) 
PROV TEE Viees. 40. A and Bb: 
1831— Unio asper Lea, Tr. Am. Phil. Soc., IV, p. 85, pl. IX, fig. 15. 
ANIMAL CHARACTERS. 
u 
NUTRITIVE STRUCTURES:—Branchial opening finely papil- 
lose; anal smooth; supra-anal loosely, to deciduously, connected 
to anal by mantle edges; inner gills much wider (posteriorly), 
