444 THE AMERICAN MIDLAND NATURALIST 
the most beautiful shells. It is strange that it shoud not be found 
anywhere in the Ozarks as it seems to be a mussell that rather 
prefers swift current. Yet as that is an unglaciated region without 
much sand, to which it is partial, we may account for its absence 
there in part. It is entirely supplanted in the Osage by fallactosa. 
From the writer’s breeding record for this species it is bradytictic. 
Lampsilis fallaciosa Smith.’ 
(‘Slough Sand Shell,” ‘‘Creeper.)”’ 
Pl. VII, Figs. 18 A and B. 
1899—Lampsilis fallactosa Smith, Bull. U. S. Fish., p. 291, pl. LX XIX; 
1g00a, Simpson, Pr. Ac. N. Sci. Phila., p. 74, pl. II, fig. 5- 
ANIMAL CHARACTERS:—lIdentical with L. anodontotdes in 
every respect, except perhaps in glochidial characters. 
SHELL CHARACTERS :— Differs from anodontoides in possessing 
a smaller, lighter, thinner shell; a more prominent post-umbonal 
ridge; more pronounced beak sculpture; pinkish nacre in umbonal 
cavity; bright yellowish, or olivaceous epidermis with bright 
green rays all over shell—especially on the posterior slope; rusty 
red color often for umbonal region; a sulcus often seen just anterior 
to the post-ventral edge and extending a short distance up on the 
shell as a radial furrow. 
Sex Length Height Diameter Locality 
oO 94 x 45 x 28 mm—(Lower L. Contrary, St. Joseph) 
@ 64 x 30 x 21 mm—(Chariton R., Kern) 
9 64 x 31 x 2t mm—(Miss. R., Hannibal) 
51.5 X 24.5 x 15 mm—(Osage R., Warsaw) 
Ra". 7.5 X  5.5mm—(Grand R., Chillicothe) 
The last measurement is that of a juvenile identified by Dr. 
Howard. Its beaks are sculptured by two or three subparallel 
ridges at the base of the post umbonal slope and a few very faint 
tubercles at the base of the anterior umbonal slope. Anterior end 
of the shell is greatly produced as noted in most juvenile shells 
of any species. Note the very small inflation in the above measure- 
ment. It is strange that this shell at this stage of its life should be 
practically rayless while the rayed character of the adult shell is 
its chief feature. 
MISCELLANEOUS REMARKS:—Fallactosa may have developed 
from anodontoides for ecological reasons, This little striped shell 
