STERKIA. 



57 



6. STERKIA CALAMITOSA (Pilsbry). PI. 7, figs. 1 to 4. 



The shell is perforate and rimate, cylindric, obtuse at both 

 ends, thin, somewhat glossy, light brown. First I 1 /? whorls 

 smooth, corneous, the rest sculptured with close rib-striae, not 

 quite as wide as their intervals, and somewhat less regular 

 and close on the last iy 2 than on the second whorl. There are 

 41/2 to 4% whorls, the upper ones strongly convex, the last a 

 little less so, its latter part flattened laterally, distinctly im- 

 pressed over the upper palatal plica, and having a dent-like 

 impression on the base, near the expansion of the lip. The 

 aperture is as wide as long, obstructed by five teeth. Angular 

 lamella slightly curved, the concavity towards the periphery, 

 outer end reaching the lip ; its summit is bilobed, there being 

 a median depression. The parietal lamella is of about the 

 same length, but it is higher, more deeply placed and slightly 

 sinuous; its crest is bent towards the angular lamella. The 

 columellar lamella is very large. It consists of a horizontal 

 portion running forward on the parietal wall near the colu- 

 mella, and a broad, vertical portion descending to the base of 

 the axis (pi. 7, figs. 3, 4). The two strong palatal folds stand 

 rather deep within, the upper (seen in profile in fig. 1) being 

 about twice as long as the lower. Peristome is rather broadly 

 expanded and reflected, brown, thin ; narrower, somewhat 

 excavated in the sinulus; terminations rather remote, joined 

 by an appressed callus. 



Length 1.5, diam. .75 mm. 4% whorls (type). 



Length 1.45, diam. .8 mm. 4y 2 whorls (E. de Todos Santos). 



Lower California, near the mouth of San Tomas River 

 (Hemphill, type loc.) and Ensenada de Todos Santos (C. R. 

 Orcutt). 



Pupa calamitosa PILS., Nautilus, iii, Oct. 1889, p. 61, pi. 1, 

 fig. 7; Proc. A. N. S. Phila., 1889, p. 411, pi. 12, f. 16 (1890). 



This species is related to S. kemphilli, but in that form the 

 upper palatal fold is much longer, the vertical portion of the 

 columellar lamella far less broad, and the angular lamella 

 longer; the lower palatal fold is wholly immersed, and there 

 are many other differences in structure, $. kemphilli being a 

 more evolved species. 



