354 THE AMERICAN MIDLAND NATURALIST 
base, each being marked by a muscilaginous substance. The 
umbonal markings of this flat straw-colored juvenile shell consists 
of four broadly inverted V-shaped ridges the rear line being finer, 
longer and closer together, extending down the posterior umbonal] 
ridge. 
MISCELLANEOUS REMARKS:—L. fragilis is distinctly a river 
form for this State, although we would naturally think that this 
alated and thin-shelled species would be established in the lakes 
and other quiet waters of Northwest Missouri, especially where 
it predominates the streams. Breeding records for this species 
show that it may bear glochidia every month of the year except 
for a few weeks in mid-summer; hence, a very long period breeder. 
It was found in August distending its ovisacs with water preparatory 
to ovulation. Only two other species possess smaller glochidia— 
those of Amygdalonajas donaciformis (Lea) and A. elegans (Lea) 
with which fragilis is closely related; however, external characters 
of shell alone—especially as to size and form—show no close con- 
nection. Fragilis may be distinguished from other similar alated 
forms by its peculiar yellow surface, marked by brown horn-colored 
restlines, depressed umbones, green rays in young and broadly 
elliptical outline in old specimens, if their alae are lost as is often 
the case. Through special cooking tests the writer has found 
out that nearly all the soft parts of this species is very edible. 
It is also economically important in producing pearls, since it is 
easily parasitized. No mussel is more active and as it anchors 
itself so firmly it is often extracted from its bed with great 
difficulty. The straw-colored and green rayed juveniles are easily 
located, not so much by color as by their “‘tracks”’ since they are 
the most active crawlers. This species is the most abundant in the 
One-Hundred-and-Two, Platte, Grand, Tarkio, Osage—in fact all 
the streams of Northwest and Central Missouri as determined by 
personal collections. It is poorly developed in the Osage and is not 
found at all further South in the clear-water streams of the Ozarks. 
Simpson reports it for the Missouri River, but I think he means 
only for the tributaries of the Missouri as no mussel life is actually 
reported in the main stream of this River throughout the State. 
Its general distribution is for the entire Mississippi River drainage; 
St. Lawrence system; Red River of the North; Eastern Texas 
and Cumberland River. 
(To be continued.) 
