154 



TERRESTRIAL AIR-BREATHING MOLLUSKS. 



PATULA, IIald. 



Fig. 59. 



Animal of Patula solila 



Animal heliciform ; body elongated, semi-cylindrical, tapering to a point 

 posteriorly, convex above, plane beneath; mantle simple, central, not extend- 

 ing beyond, and accurately fitting to the peristome of the shell, into which 

 the whole animal may retire ; head obtuse ; eyes at the end of long, cylindrical, 

 retractile peduncles; tentacles short, retractile ; generative orifice on the side 

 of the head, behind the right eye-peduncle; respiratory orifice in the collar, at 

 the angle of the aperture of the shell, anal orifice immediately adjoining; no 

 caudal mucus pore, no locomotive disk. 



Shell widely umbilicatcd, depressed, diseoidal, turbinate, rugose, or eostu- 

 lately striate; whorls 4-6, equal or gradually increasing; aperture lunately 

 rounded ; peristome simple, straight, acute. 



As there appears considerable confusion in regard to the limits of the genus, 

 I think it best to make no reference to any species foreign to Korth America. 

 Here it ranges over both the Central and Eastern Provinces. 



In none of the American species of this genus have I found a jaw with dis- 

 tinct well-formed ribs as in Helix. In several species, however, such as slrigosa 



Fig. CO. 



Fig. 61. 



.law of Patula asteriscus (Morse). 



Patula striatella (Morse 



and Cooperi, there are distinct traces of subobsolete ribs near the cutting mar- 

 gin, and still more so in incruitala. In astei'iscus there arc coarse wrinkles, 

 resembling subobsolete ribs. In perspectiva, striatella, and Idahoensis there are 

 such wrinkles, and also coarse vertical striae. I have not found the stria? as 

 oblique as shown in Fig. 61. In solitaria, alleniata, and Hempltilli there are no 

 traces of cither ribs, wrinkles, or stria?. In all these species there is a tendency 

 to a median projection to thy cutting edge. This is greatly developed in soli- 

 taria, alternata, Cumberland iana (with perpendicular stria?), and especially in 

 Hemphilli. The last two species have also a much more arcuate jaw than the 

 other !. I have not seen the jaw of Horni or pauper. 



