UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 19, No. 9, pp. 299-316, plates 15-17 December 6, 1919 



THE OCCURRENCE OF A ROCK-BORING ISOPOD 



ALONG THE SHORE OP SAN PRANCISCO 



BAY, CALIFORNIA 



ALBERT L. BARROWS 



0€C, 



CONTENTS 



PAGE 



Introduction 299 



Occurrence and habits of the Sphaeromidae 300 



Other boring species of Sphaeromidae 302 



Occurrence of Sphaeroma pentodon Richardson 305 



Process of boring of Sphaeroma pentodon Richardson 306 



Summary 310 



Bibliography 310 



INTRODUCTION 



Near the railway station of Rodeo, on the shore of San Pablo Bay, 

 in the northern portion of San Francisco Bay, California, there are 

 ledges of Pinole tuff and San Pablo sandstone into which inn line 

 isopods have bored in great numbers. These isopods have been iden- 

 tified as Sphaeroma pentodon Richardson by Dr. Harriett Richardson 

 Searle of the Smithsonian Institution, to whom I am indebted for the 

 courtesy of examining them. The other elements of the associated 

 fauna of this locality are mainly small barnacles, bryozoans, small crabs 

 and pelecypods of the species Mya- arenaria Linnaeus and Mytilus 

 edulis Linnaeus. Some of the latter species are found in the holes of 

 the isopods. 



The water of this part of San Francisco Bay is brackish, but the 

 salinity varies greatly during the year, its degree being determined 

 bv the amount of water discharged into the bav bv the Sacramento 



