26 WEST COAST SHELLS 



founded with N. exigua, Sby., which is a Panama 

 shell, smaller, more inflated, and with less conspicu- 

 ous sculpture. There are a few other species of 

 Nucula to which names have been given, but they 

 are uncommon and difficult to determine, and it 

 does not seem wise to give them here. The purpose 

 of this book is to describe all of the species which 

 the ordinary collector will be likely to find, as well 

 as most of the conspicuous rare shells. In due time 

 it is hoped that an official book will be published 

 by the National Museum, giving a complete list of 

 all the species that have ever been collected on this 

 coast, with the limits of their locations. The diffi- 

 culties of making a complete book of this kind are 

 very great, however, especially since so many species 

 have received different names at various times, and 

 only the best informed naturalists are competent to 

 decide which should be retained as the true ones. 



Figure 1 1 represents Leda ha- 

 mata^ Cpr., the Hooked Leda, 

 though the picture is nearly three 

 times as lon^r as the real shell, as is 



Fig. U, X 1 (*) - . 



indicated by the fraction. The 

 shell is compressed and is of a dark chestnut-brown 

 color. The specimen was obtained by dredging near 

 Catalina Island, in about 300 feet of water. 



Another species, considerably larger than the last, 

 but not quite so long as the figure, is he da taphria^ 

 Dall, the Grooved Leda. The name is taken from 

 the Greek, and indicates that the shell is full of 

 ditches or furrows. The shell is as round as a fat 

 bean, and there are more grooves on the sides than 



