THE PACIFIC COAST. 27 



SYNONYMS AND REFERENCES. 



Melarnpus olivaceus Carpenter, in Riegen Cat. of British Museum, p. 178. 

 anno. 1857. 



DESCRIPTION. 



Animal not yet observed. 



Shell small, rather smooth, conical ; spire depressed, ob- 

 tusely angulated below the suture, which does not dis- 

 tinctly separate the whorls ; color dirty white, with irregu- 

 lar patches or revolving lines of dark red or purplish ; 

 epidermis olive-colored ; on young or very fresh specimens 

 there are sometimes microscopic revolving lines near the 

 base of the shell, and on the spire, which cross the delicate 

 lines of growth so as to present under the microscope a 

 granulated surface ; whorls 7 to 9, the upper ones distin- 

 guished only by means of the lens, and flattened ; aperture 

 long, equalling H of the shell, edge variegated in color by 

 the termination of the reddish bands on the white ground 

 of the shell, within white ; the outer lip is furnished with 

 numerous sharp, white laminae, in the specimens before 

 me varying from 1 to 9 ; the parietal wall of the aperture 

 is covered with an almost imperceptible, shining, callus ; 

 there is one constant, prominent, elevated white tooth- 

 like lamina revolving within the shell, which is usually 

 placed within two smaller shorter ones ; on the columella 

 there is also a stouter lamina entering into the aperture, 

 and passing outwards and curving downwards so as to 

 join the termination of the labium. 



Long. 13; diam. 18 mill. 



Geographical Distribution. Mazatlan, (Riegen Cat. 

 not uncommon,) San Diego, (Mr. W. P. Blake, in Smith- 

 sonian Collection). 



Remarks. This is the first species of the family Auri- 

 culacea found on the Pacific coast of North America. 

 There were numerous specimens found by M. Riegen, 

 which Mr. Carpenter describes as distinguished generally 



