EASTERN PROVINCE ^INTERIOR REGION SPECIES. 33t 



Jaw with an upper, quadrangular, accesoory plate. The jaw is strongly 

 FiG.^5. ^ arched, the ends acuminated in I'lr-.^oo. 



S. avara (Fig. 3G6), blunt in ohll 

 qua, ovalis, Totteniana (Fig 305), 

 cam pest rifi, Uueafa, and effum. 

 There is a median projection to 

 ""W^ the cutting margin, sometimes -^i^vciiw. „,■,„•,/. 

 Jaw of *■. Toitowajirt. (Morse.) brolvcu by the cudsof ribs. These ril>s are found 

 in S. Totteniana (3) (see Fig. 305), S. ohliqua (3-7), om//.v (over 7) ; I de- 

 tected no ribs on that of 8. avara, Jineafa, aampestris, Nuttalliana, Mlli- 

 mani, Haydeni, or effnsa. 



The general arrangement of the lingual membrane is as in Patula. 

 The characters of the separate teeth are seen in Terr. Moll., Y, Tlate X, 

 Fig. K. The peculiar character of the dentition is the cutting away or 

 thinning of the middle portion of the lower edge of the base of attach- 

 ment in the central teetli, and the inner lower lateral angle of the base 

 of attachment in the laterals and still more in the marginals. The 

 marginal teeth are also often peculiar in the denticulation of their re- 

 flected cusps. They have usually two small outer side cusps, the inner 

 the smaller, each bearing cutting points proportioned to their size. 

 The reflection of the- teeth is also small in proportion to the base of 

 attachment. In other respects the dentition of the genus is very much 

 like that of the Helicidce. 



The genital system in the species examined by me presents one pe- 

 culiarity which may prove a generic character : the testicle is not sep- 

 arated into distinct fasciculi by the parenchyma of the liver, but forms 

 a single mass. The prostate gland, also, is very much swollen, and 

 extends only about the half of the length of the oviduct. 



Siiccinea rettisa, Lea. 



Shell ovate oblong, very thin, pellucid, yellowish; spire short; 

 Fin. 3G7. whorls 3 ; aperture below dilate and drawn back. Diameter, 

 .3 inch ; length, .7 inch. 

 Ohio, near Cincinnati. 



A single specimen only of this species has come into my pos- 

 session. It differs so much from any of the described species 

 in the dilatation and retraction of the inferior part of the aper- 

 ture that I have not hesitated to consider it new. (Lea.) 

 1749— Bull. 28 22 



