204 SHELLS OF SAN PEDRO. BAY—WILLIAMSON. 
Family AMALTHEIDZ. 
Genus AMALTHEA Schuin., 1817 (Hipponyx Detrance, 1819.) , 
Amalthea antiquata Linn. 
Empty shells are washed ashore at the bay. A few found living 
with A. tumens, nestled close to some big Chitons (Maugerella conspicua) 
in a cleft of rock at Point Fermin. 
Amalthea cranioides Cpr. 
Rare; with A. antiquata. This shell is flat and has the apex near 
the center. 
Amalthea serrata Cpr. 
Two or three found at San Pedro. These shells have a brown epi- 
dermis, in irregular patches. 
Amalthea tumens Cpr. 
With A. antiquata, but not so plentiful. 
Family VERMETID. 
Genus SERPULORBIS Sassi. 
Serpulorbis squamigerus Cpr. 
Less plentiful than the variety below. 
Serpulorbis squamigerus Cpr., var. pennatus Morch. 
Usually found in colonies on the rocks. 
Genus BIVONTA Gray. 
Bivonia compacta Cpr. 
Only dead shells found; rare. (J.G.C.) 
Genus SPIROGLYPHUS Daudin. 
Spiroglyphus lituella Mérch. 
On kelp; Catalina Island and Portuguese Bend. (R. E. C. 8.) 
Family CACID. 
Genus CAiCUM Fleming. 
Czcum crebricinctum Cpr. 
Ten or twelve found at San Pedro;dead. (C.T.S. 
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