180 PROCEEDINGS OF THE ACADEMY OF 



P. solitaria (pi. VII., fig. 9) has 25 — 1 — 25 teeth, with 14 perfect 

 laterals. The transition to marginals is very gradual. 



P. Cooperi (pi. YII., fig. 2), 29—1—29, with 11 perfect laterals. 



P. Hemphilli (pi. VII., fig. 6) has 20—1—20 teeth, with 7 perfect 

 laterals. 



P. Idahoensis (pi. VII., fig. 4) has 33—1—33 teeth, with 14 

 perfect laterals. The transition from the laterals to the marginals, 

 however, is very gradual. 



P. Haydeni not examined. 



P. alternata (pi. VII., fig. 5). One membrane has 121 rows of 

 34 — 1 — 34 teeth, ten of which are perfect laterals. The varietj'' 

 moy^dax^ pi. VII., fig. 7, agrees with it in dentition, except the 

 number of teeth. I counted 20 — 1 — 20, with 5 pex'fect laterals. 



P. Cumberlandiana (pi. VII., fig. 8) has 24 — 1 — 24 teeth, with 

 about 13 perfect laterals. There is an appearance of a side cutting 

 point to the third tooth, a decided one beyond the sixth. 



P. tenuistriata, not examined. 



P. perspectiva (pi. VII., fig. 3), 15 — 1 — 15 teeth, T perfect 

 laterals. 



P. striatella (pi. VII., fig. 10), 20—1—20 teeth, with 8 perfect 

 laterals. Moi*se gives 16 — 1 — 16. 



P. vortex (pi. XX., fig. 4), 18 — 1 — 18, with 8 laterals. A marginal 

 tooth is shown in h. 



P. Ingersolli, Bland. The species should, perhaps, be placed 

 in Microphysa. Jaw of same type as in H. Lansingi (above), with 

 22 ribs. Teeth 16 — 1 — 16, with a gradual change from laterals to 

 marginals. The latter are low, wide, with one inner, long, blunt 

 cutting point, and one outer, small, blunt. The side cusps and 

 cutting points of centrals and laterals are well developed. 



P. pauper^ Horni, inctnistata, not examined. 



P. asteriscus (pi. XVIII., fig. 9). Morse gives 71 I'ows of 

 13 — 1 — 13 teeth ; 6 perfect laterals. I counted 11 — 1 — 11, with 5 

 perfect laterals. The reflected portion of the central teeth is quite 

 small. The marginal teeth are like those of Pupa. 



It will be seen that Patula differs from all the preceding genera 

 by the presence of quadrate, not aculeate, marginal teeth, a 

 character shared by all the succeeding genera. There does not 

 appear any very essential character in the dentition by which to 

 distinguish it from many of American sub-genera of Helix, as will 



