1889.] NATURAL SCIENCES OF PHILADELPHIA. 411 



NEW AND LITTLE-KNOWN AMERICAN MOLLTJSKS, No. 2. 

 BY H. A. PILSBRY. 

 Pupa calamitosa Pilsbry. PI. 12, figs. 16, 17. 



Shell minute, cylindrical, very blunt at apex, chestnut colored ; 

 whorls -U, the first one and one-half smooth, the following regularly 

 costulate striate, the costulse separated by spaces wider than them- 

 selves ; last whorl abruptly turning forward, rounded beneath, 

 encircled by a slight central constriction or furrow ; aperture about 

 one-third the total length of shell, rounded, truncated above, con- 

 tracted within ; peristome thin, expanded, Avithout crest or callous 

 thickening behind ; columellar margin rather dilated ; parietal wall 

 bearing two entering lamelke, one arising near the termination of 

 the outer lip, the other more deep seated, elevated, entering less 

 obliquely ; columella with a strong white deep-seated obliquely 

 entering fold ; outer lip with two short white lamella?. 



Alt. 1-70, diam. -80 mill. 



Two trays of this tiny species are before me. One received from 

 Henry Hemphill, collected near the mouth of San Tomas river, 

 Lower California, the other collected by Orcutt near San Diego, 

 Cal. Most specimens show the widening inward of the outer lip 

 shown in the figure. Several specimens have only one lamella on 

 the outer lip, and are rather larger than the typical form described, 

 measuring 1*90 mill. alt. The second parietal lamella is usually 

 much larger than the first, but in one or two specimens before me 

 this is not the case. The umbilical rimation terminates in a tiny 

 depression, perhaps minutely perforated at the axis. The formula 

 of denticles or folds (according to Dr. Sterki's scheme*) A A B D E 

 or AA B E. The species is of a decidedly different type from any 

 known American Pupa. P. hordacea, californica, and rowelli, 

 abundant western forms, belonging in quite diverse groups ; the 

 first being allied to P. corticaria and pellucida, the latter grouping 

 with P. decora, rowelli and corpulenta. 



From the Pupa, of the Mexican fauna, leucodon, pellucida and 

 chordata the present species is quite distinct in every respect. 



The inward continuation of the parietal and columellar folds is 

 shown in figure 17. They are white, regularly veined with darker, 

 like polished plates of agate. 



* See Proc. U. S. Nat. Mus. 1888, p. 369. I have repeated the letter represent- 

 ing the parietal fold, as the two seem to be of equal importance. 



