GASTEROPODS 359 



animal is removed, it displays a most beautiful and highly colored 

 nacreous surface. The spot near the center of the inner shell 

 surface where the muscles of the foot were attached is usually 

 most brilliantly colored. The shell of the abalone is susceptible 

 of taking a very high degree of polish, and is extensively used in 

 commerce for colored mother-of-pearl and for inlaid work. Hal- 

 iotin is a vegetable-feeding genus. They cling with great tenacity 

 to rocks about low tide, and it requires skill to remove them with- 

 out breaking the shell. There are several species in California. 

 The Chinese use the abalone for food, and have waged a persis- 

 tent war upon the family along the Pacific coast until the speci- 

 mens are not nearly as common as formerly. They are also eaten 

 in France and in Japan. 



H. spleridens. The largest and perhaps the most attractive in 

 appearance of the Californian species. Speaking of this beautiful shell, 

 Professor Keep says : " Within, a whole rainbow is condensed in one of 

 the magnificent shells, though the shades of green are most conspicuous. 

 The coloring in the center is particularly fine, resembling a peacock's 

 tail. There are about six open holes near one side of the shell, and its 

 length is about the same number of inches." (Plate LXVI.) 



H. rtifescens. A large abalone, which sometimes attains a length of 

 eight or nine inches. It is red in color, with three open holes in the 

 body-whorl. The outer portion of the shell is usually incrusted with 

 mineral deposit and overgrown with vegetation. 



H. craclierodii. Very dark green without, with five to nine holes ; 

 length from one to six inches ; spire exceedingly short. Common on the 

 Californian coast in crevices of rocks at low tide. 



FAMILY TBOCHHXE 



This is one of the largest and most interesting families of the 

 Mollusca. It contains many apparently widely separated genera 

 and a host of species, which for the most part are littoral, the 

 majority actually living between tide-marks. The typical trochid 

 shell is top-shaped or pyramidal, having a broad base and many 

 closely wound flat whorls terminating in a sharp apex. All the 

 trochids are nacreous within the aperture a character which is 

 constant throughout the family. The animal has but one gill 

 (the left), a short snout, and often frontal lobes on the head. 

 The edge of the mantle or the epipodial line of the foot is usually 

 ornamented with from three to five cirri. The tentacles are 



