MOLLUSCA OF MICHIGAN— WALKER. 499- 



A species of the Northern region found only as yet in Ontonagon and 

 Marquette counties, and at Ohvet, Eaton county. Distinguished by its 

 slender form, Hght color and strongly ribbed jaw. 



PALLIFERA HEMPHILLI (W. G, Binney). 



Animal long, narrow, cylindrical, with a pointed 

 tail. Black. Jaw strongly arched with a median 

 projection and four or five ribs, all concentrated 

 p. hemphm. (Binney.) on the middle third, the outer thirds being rib- 

 less. Length (in alcohol) 25 mm. 



T ebennophorus hemphilli, W. G. Binney, Man. Am. Land Shells, 247, 



(1885). 

 Originally described from North Carohna and Georgia, this species has 

 recently been taken in Ontonagon county and at Ann Arbor. Easily dis- 

 tinguished from P. dorsalis by its color and the peculiar arrangement of the 

 ribs on the jaw. 



II. HETERURETHRA. 



Superfamily ELASMOGNATHA. 



Family SUCCINElDyE. 



Tentacles but little developed or wanting. Jaw surmounted by an ac- 

 cessory quadrangular plate. Central tooth of the lingual membrane tri- 

 cuspid, of, the same size as the laterals, which are tricuspid or bicuspid, of 

 the type of the Helicidce. Marginal teeth quadrate, with narrow base, 

 multicuspid reflection, serrate by the splitting of the inner cusp into numer- 

 ous denticles. Shell external or internal, very thin, transparent, spiral. 



Genus SUCCINEA (Draparnaud) . 



Shell imperforate, thin, ovate or oblong; aperture large, obliquely oval, 

 columella simple, acute; peristome simple, straight. 



Animal heliciform, thick and blunt before, short and 

 pointed behind; mantle central, simple, protected by a 



^^^- ^-^sss^ ^::^ shell which does not conceal the whole retracted ani- 



^^^^^ ^'=^~** mal; respiratory and anal orifices on the right of the 



Animal of "5wranea mantle edge under the peristome; generative orifice be- 



(Binney.) ' hind the right eye-depuncle; no caudal mucus pore. 

 Jaw with an upper, quadrangular, accessory plate; strongly arched, the 

 end acuminated or blunt, wdth a median projection to the cutting margin, 

 ribbed or smooth. 

 48 



