BULIMULUS-PLICOLUMNA. 153 



tour of the Chilian B.pupiformis (vol. X, p. 138), but with totally 

 dissimilar apical sculpture. The South American and Lower Cali- 

 fornian species inhabit similarly arid, mountainous regions. 



B. ABBREVIATUS (Cooper). PL 20, figs. 80,81. 



Nuclear whorls 1?, vertically flattened, the others reduced to 8 or 

 9j, the 7th largest, 6th and 8th about equal and much smaller, pe- 

 nultimate not narrowed and larger than fourth. Outline swollen at 

 middle, contracted at suture of body whorl, which is shorter verti- 

 cally than in C. ramentosa. Mouth subcircular, subacutely pointed 

 at its apex, near suture, the constrictions on body whorl deep, partly 

 visible inside, otherwise as in ramentosa. A very thin brownish 

 epidermis covered the living shell. Length 0'85, breadth 0'19 inch ; 

 mouth 0-22 long, 0'18 wide (Cooper). 



Sierra Laguna and El Taste Mts., 4200 ft. alt., Lower California. 



Columna ramentosa var. abbreviata J. G. COOPER, Proc. Cal. 

 Acad. Sci. (2), iii, p. 215. Columna (var. f) abbreviata COOP., t. c., 

 p. 338, pi. 13, f. 2. Columna (ramentosa f) abbreviata COOP., 1. c., 

 p. 140, pi. 6, f. 18, 31. 



Dall writes of this form as follows: " Dr. Cooper tells us that his 

 ' Columna' ramentosa abbreviata has the apex, surface, and general 

 form of B. artemesia, but with a gyrate pillar and pervious axis in 

 the last whorl. In the only specimen I have seen of variety abbre- 

 viata, the axis is not pervious and the shell is pathologically dis- 

 torted. I do not doubt that some of Dr. Cooper's examples of this 

 form (of which only nine specimens were collected in two years) 

 have a pervious axis, but I am inclined to regard the shell as a 

 variety of B. artemesia rather than C. ramentosa, and as a peculiar 

 pathological product rather than a normal development. I fully 

 agree to the proposition that B. abbreviata, if it is normal, presents 

 characters (analogous to the gyrate axis of Leptobyrsus spirifer in 

 its penultimate whorl) in many respects intermediate between B. 

 artemesia and ' Columna ' ramentosa, and that all three are derived 

 from the same stock." 



In the uncertainty as to the status of this form it may best stand 

 provisionally as a distinct species. 



B. RAMENTOSUS (Cooper). PI. 20, figs. 82, 83, 84, 85. 



Shell narrowly rimate, slender, pillar-shaped, the apex squarely 

 truncated, 6 or 7 earlier whorls gradually tapering, those below of 

 about equal diameter. Dull brown. Surface lusterless, with sculp- 



