LX SySovEsArTiGe DISCUSSION OF “SPECIES. 
Family LYMN/A®ID/ZE Broderip, 1839. 
Subfamily LyMN21In Dall, 1870. 
SHELL: Normally dextral, rarely sinistral, ovately-oblong or 
elongate; spire more or less attenuated; columellar axis thickened by 
a shelly deposit and typically gyrate or twisted; peristome thin, sharp; 
shell covered with a corneous periostracum or epidermis. 
AnimaL: With a short, wide, rounded foot; head supporting a 
velum which is retained from the larval state; tentacles flattened, tri- 
angular, the eyes sessile upon their inner base; a large superior and 
two smaller, narrow, lateral jaws present; central tooth unicuspid, 
lateral teeth bi- or tri-cuspid, marginals serrated; kidney very large, 
wide, pear-shaped ; ureter proceeding directly forward without flexure; 
buccal retractors two in number, very long, inserted distally in the 
columellar muscle, the right retractor near the penis retractors and 
the left retractor some distance from this point; genitalia with the 
genital apertures separated, that of the male being behind the right 
tentacle, while that of the female is at the base of the neck near the 
pulmonary opening; the male organs consist of penis, penis-sac, vas 
deferentia, and prostate; the female organs consist of vagina, oviduct, 
receptaculum seminis and one albuminiparous gland with two accessory 
glands; an ovotestis and ovisperm duct are common to both male and 
female systems. The penis and penis-sac are retracted by one or more 
powerful muscles which are inserted in the columellar muscle. The 
body of the animal is striated, not granulose as in the helices. 
DIsTRIBUTION: Worldwide, but more numerous in the north tem- 
perate zone. 
GEOLOGICAL RANGE: Upper Jura (Purbeck) to recent fauna. 
Maximum development in late Tertiary times. In America the family 
ranges as far back as the Comanchean Period. 
As restricted above, the Lymnzinz form a markedly uniform and 
well-characterized group of the fresh-water Pulmonata. 
