246 WEST COAST SHELLS 



color. Live specimens, varying from one-fourth of 

 an inch to six inches in length may be found at low 

 tide, clinging to the rocks, particularly in the most 

 inaccessible cracks, and under heavy boulders. 



When examined in a large jar of sea-water, as all 

 of these animals should be if there is an opportunity, 

 a living specimen presents many interesting points 

 for study, particularly its broad toot, its fringed and 

 sensitive mantle, its mouth and eyes and slender 

 tentacles. Care must be taken to change the water 

 very often, if the animal is to be kept alive any 

 length of time, as it is very sensitive to confinement 

 and rapidly uses up the dissolved oxygen in a jar of 

 water. 



Haliotis corrugata^ Gray, the Corrugated Aba- 

 lone, resembles H. rufescens in size and color, but 

 the shell is nearl}^ circular, thick, high arched, and 

 externally corrugated. It has only two or three open 

 holes, but these are quite large, and the central 

 muscle impression is wide and very brilliant. It is 

 a southern species, and it is usually found beneath 

 the low water mark. 



Haliotis assimilis^ Dall, the Threaded Abalone, 

 is now considered to be a distinct species, instead of 

 a mere variety. It lives in deep water, from Mon- 

 terey to San Diego. A specimen from the latter 

 port measures four inches in length and three and a 

 quarter in breadth. It has seven open holes, and the 

 exterior of the shell is marked with many threads, 

 like ta[)estry carpeting. There is a moderate fur- 

 row below the line of holes. The spire is short but 

 quite distinct, and the body of the shell is high 



