272 ' THE AMERICAN MIDLAND NATURALIST 
Sex Length Width Diameter Locality 
9. 35. x24 x) 2e -— (White -R.; Hollister; Mio.) 
of 9°26 ox! 28. x ro" (Jack's. Fork,” Shannon? Coy) 
9 18 x «1 x 7.5mm—(Jack’s Fork, Shannon Co.) 
The latter is a juvenile, tawny in color, with beak sculpture 
extending well out upon the disk in undulated bars, showing 
here, as in so many of the Anodontinae, that in the adolescent 
shell there is more of tendency toward disk sculpture in the indi- 
vidual, just as seen in the primitive shell of the whole race of 
Naiades. 
MISCELLANEOUS REMARKS:—This species is easily identified 
by its small shell (being never much more than an inch and one- 
half long), by its slipper-shape and by its coarse concentric sculp- 
turing. It is a great burrower and, although it may be abundant, 
it may escape notice because of this habit. For this state calceolus 
is only found in the streams of the south slope of the Ozarks where 
it is found in company with its nearest relative Alas. marginata, 
and is found in greatest numbers in Jack’s Fork of the Current 
River, Shannon County. It is found rather common in the streams 
of Arkansas, and has a general distribution in the Ohio, Tennessee 
and Cumberland Rivers; also the Lower and Middle St. Lawrence 
systems. Being found with mature glochidia in late Fall it can 
be classed as bradytictic. 
Alasmidonta marginata Say. 
(‘ Nigger. ‘Toe,’’ “\ Elk: Toe.”*) 
Pl. XXIV, Fiss.-78 A and B. 
1819—Alasmidonta marginata Say, Nich. Inc., No. 1. 
1843—Alasmidonta corrugata DeKay, Zool. of N. Y., Pt. 5, p. 198, 
Pl. XXAV, figs 250: 
ANIMAL CHARACTERS. 
NUTRITIVE STTRUCTURES:—Branchial opening densely papil- 
lose; anal with fine papillae; supra-anal moderately separated 
from anal, mantle-edges marked with squarish black blocks at 
regular intervals; outer gills wider than inner; inner lamina of 
inner gills connected with visceral mass; palpi very long and 
united for one-half of their length antero-dorsad; foot very long 
and powerful, orange colored; other parts tannish colored. 
REPRODUCTIVE CHARACTERS :—Marsupium with wavy crowded 
septa when sterile; greatly distended when gravid, bluish with 
ciate 
