THE NAUTILUS. 27 



As Dr. Cooper observed, this species is not as " protean " as some 

 others. It exhibits no such variations in form or color as B. proteus ; 

 the latter assumes almost every mutation of form, but taken on the 

 average is less acute and has the last whorl less patulously drawn 

 out, axially, than the B. montezuma. The color of B. proteus is 

 variably distributed, but tends in the most strongly colored exam- 

 ples to be laid on in 4-6 broad, spiral bands of brown, with indis- 

 tinct boundaries, separated by paler zones. In B. moniezuma the 

 color is seldom present, but, when it is, it is laid on in narrow, 

 obscure zones, parallel with the incremental lines and never spirally 

 disposed. The granulation in the Californian shell is less coarse 

 and intense than in the Peruvian species when most developed, and 

 the umbilicus averages much smaller in the former. All these char- 

 acters are of degree rather than kind, but two features may be men- 

 tioned which appear constant and s«pecific. In the Mexican shell 

 the angle which the outer lip makes with the body whorl, or axial 

 perpendicular, at its junction is invariably more acute than in B. 

 proteus, which latter has the lip bent suddenly down at this point. 

 Secondly, the larval shell or nucleus of B. proteus is beautifully 

 shagreened with minute jjunctations or short, almost vermicular, 

 indentations, visible plainly under a glass, and only absent when 

 worn off by abrasion. Traces of this sculpture may always be found. 

 In B. montezuma the nucleus is delicately ribbed in harmony with 

 the incremental lines, and does not show the peculiar shagreeniug 

 alluded to, a character which alone is sufficient to establish its dis- 

 tinctness, but the constancy of which could not be predicated from 

 the three specimens examined by Mr. Binney. 



The distribution of the species now determined by Messrs Eisen 

 and Belding is sufficient to disprove the hypothesis of introduction 

 by artificial means, and it is satisfactory to have our largest North 

 American species placed upon a permanent footing. 



EDIBLE MOLLUSKS OF SOUTHERN CALIFORNIA. 



BY MRS. M. BURTON WILLIAMSON, UNIVERSITY, LOS ANGELES CO., 



CAL. 



In an interesting article upon the " Edible MoUusks of Rhode 

 Island," by Mr. Horace F. Carpenter, published in the Nautilus 

 some time ago, he compares the number of marine edible mollusks 

 of Rhode Island with those reported from San Francisco by Profes- 

 sor Keep. 



