348 THE AMERICAN MIDLAND NATURALIST 
(Raf.), but, as stated before, it takes the place of the latter wholly 
in North Missouri. The North Missouri Grand River bears dona- 
ciformts in its most typical form. The writer finds this species 
most colonial in their habits, and has been able to find many of 
them nearly every month of the year, but has not found any 
gravid during the winter. The earliest date for the bearing of 
glochidia is June r9th. No previous public record has ever been 
made of this unique glochidium. From the above data it may be 
inferred that it is not bradytictic as is mostly the breeding habit 
of the Lampsilinae. ‘This little mussel] is also eccentric in that while 
in the parasitic stage it develops an adult shell five times the size 
of the glochidial one. Surber (1913, p. 1og) finds that its specific 
distributor is ‘‘Sheep’s Head” (A. grunniens). 
Amygdalonaias truncata (Rafinesque). 
(‘‘ Deer-Foot,”’ or ‘‘ Deer-Toe.’’) 
XXV, Fig. 88 A and B. 
1820— Unio truncata Rafinesque, Ann. Gen. Sci. Phys. Brux. 
1831— Unio elegans Lea, Am. Phil. Soc., IV, p. 83., pl. fig. 13. 
1898—Plagiola elegans Baker, Moll. Chicago, Pr. I, p. 91, pl. XXI, 
fig. 1; 1900b, Simpson, Pr. U. S. Nat. Mus., XXII, p. 604. 
1912b—Amygdalonaias elegans (Lea) Ortmann, An. Car. Mus., XXII, 
p. 328. 
ANIMAL CHARACTERS. 
NUTRITIVE STRUCTURES :—Identical with those of donaciformts. 
REPRODUCTIVE STRUCTURES:—Branchial mantle margin a 
little more thickened with slight crenulations than in donaciformis; 
glochidia a little larger, measuring 0.060 x 0.070 mm—otherwise 
these structures are identical with those of donaciformts. 
SHELL STRUCTURES. 
EXTERNAL STRUCTURES:—Shell short, roundly triangular, 
inflated; post-umbonal ridge sharply angulated from beaks to 
posterior point of shell; disk smooth; beaks rather prominent, 
sculptured with a few fine ridges more or less double-looped or 
sinuated; epidermis yellowish, brownish or even grreenish with 
beautiful paintings of green broken by arrow-marked rays; no 
sex dimorphism of shell, both sexes being rather swollen post- 
ventrad. 
INTERNAL STRUCTURES:—With the exception of a deeper and 
