NATURAL SCIENCES OP PHILADELPHIA. 203 



laterals. The marginals figured are from the portion of the mem- 

 brane where they are the least developed as to their cutting points. 



H. Hazardi (pi. VIII., fig. 5) has 16116 teeth with 8 laterals. 



H. oppilata. Not examined. 



H. Dorfeuilliana. Not examined. 



H. Ariadnee. Not examined. 



H. septemvolva (pi. VIII., fig. 6) has 9 laterals. I cannot 

 count the teeth or draw the marginals on the only slide I have 

 preserved. The latter were described by me as being like those 

 of fastigans. After an opportunity of examining the true sep- 

 temvolva at St. Augustine, I give a more detailed figure on pi. 

 XX., fig. 5. There are 28128 with 9 laterals. The small 

 form with five whorls differs only in having somewhat fewer teeth. 

 The form known as H. volvoxis does not differ excepting in having 

 fewer marginals: Jacksonville, Fla., specimens have 20 1 20 

 teeth. 



H. cereolus. Too late for illustration, I have received specimens 

 collected at Key West byMr.W. W. Calkins. There are 22122 

 teeth, with 9 laterals all of same type as in septemvolva. 14 ribs 

 on jaw. 



H. Carpenteriana. 22 1 22 teeth, with 9 laterals, 12 ribs on 

 jaw. 



H. Febigeri (pi. VIII., fig. 7) has 17 1 17 teeth with 9 

 laterals. 



H.pustula (pi. VIII., fig. 8) has 17 1 17 teeth with 8 laterals. 



H. pustuloides. Not examined. 



H. leporina. Too late for inserting in the plates, I have re- 

 ceived through Mr. Bland, the jaw and lingual membrane of a 

 Texas specimen furnished by Mr. A. G. Wetherby. The jaw has 

 11 ribs. There are 18 1 18 teeth, with 8 laterals, all of same 

 type as in H. fastigans. 



Subgenus Polygyrella. 



Jaw of the only known species, Helix polygyrella (pi. XVI., 

 fig. 11; very low, wide, very slightly arcuate, ends very gradually 

 attenuated : cutting margin without median projection : anterior 

 surface with numerous (even 26), broad, slightly separated ribs, 

 denticulating either margin. 



Lingual membrane (pi. IX., fig. 2) long and narrow. Teeth 27 

 1 27, with 5 perfect laterals. Centrals subquadrate, the lower 

 lateral angles but little expanded ; the upper margin broadly 



