284 THE CHICAGO ACADEMY OF SCIENCES. 
Animal: Dark horn-colored, tinged with bluish on the 
foot; head distinct, separated from the body by a constriction 
or neck, and produced into /ateral flaps or vela; tentacles tri- 
angular, rather long, flat, the eyes placed on their bases; foot 
short and wide, truncated before and roundly pointed behind, 
20.00 mill. long and g.oo mill. wide; respiratory orifice very 
large, placed near the junction of the peristome with the body 
Fia. 92. 
Animal of LIMN2A STAGNAEIS Linné. (Canadian Naturalist, Vol. II, p. 196.) 
whorl. Heart situated midway between upper and lower ends 
of columella, pulsations varying from thirty-seven to forty- 
eight per minute (Fig. 92). 
Faw: As usual. 
Radula formula: $2+543+13+14+13+,513+4#2 (46-1-46); 
central tooth as usual, a single membrane examined had the cen- 
tral tooth abnormal in possessing a denticle on the left side of 
the reflection (Fig. 93, c.); lateral teeth with a quadrate base 
of attachment, the reflection very large, reaching far below the 
base of attachment, bicuspid, the inner cusp very large, the 
outer cusp very small (the first lateral has a bifid inner cusp); 
intermediate teeth very long and narrow, bi- or tricuspid; mar- 
ginal teeth very long and narrow, four or more cuspid, the cusps 
being very blunt and small and extending irregularly along 
the outer edge of the teeth. The number of teeth seems to 
vary in different individuals: the writer has counted from 46- 
1-46 to 54-1-54; Binney (L. and F. W. Sh., p. 28) gives 40-1-40 
and (p.1§5) 47-1!-47 teeth; Bland and Binney (Am. Journ. 
Conch., Vol. VII., p. 161) give 40-1-40. It is probable that © 
the membrane having 54-1-54 teeth was abnormal. 46-1-46 
is the number generally counted by the writer (Fig. 93). 
Genitalia: Not examined. 
Distribution: North America, from the Atlantic to the 
Pacific Oceans, 
