ACADEMY OF SCIENCES. 87 



tolome Bay, Lower California, where they were taken among kelp. The 

 largest specimen measures as follows : 



Ft. In. 



Extreme length 1 °A 



From snout to posterior edge of operculum 5% 



Base of dorsal fin  • • • ? % 



Base of spinous portion of fin 3% 



Circumference in front of pectorals 10% 



From snout to origin of dorsal . . 5% 



From snout to origin of anal 11 



Length of pectorals %A 



From snout to origin of pectorals 5 fa 



Length of ventrals 3 



Triads semifasciata. Gnthr. (Mustelus felis. Ayres.) 



This is one of the commonest sharks of San Francisco and Tomales bays, 

 and is also found on the coast of Lower California. Ayres described it as a 

 Mustelus, but its teeth, though somewhat pavement-like, and, in many cases, 

 have points or cusps, whereas in Mustelus they are wholly smooth. Both this 

 species and Mustelus Californicus, Gill, are commonly called "dog-fish," but, 

 though from their small size, they resemble the real dog fish or Scylliadce, 

 they differ from them greatly in tbeir teeth, and in the absence of a nictitating 

 membrane to the eye. A large specimen, procured in this bay, measured as 



follows: 



Ft. In. 



Tip of snout to end of tail 4 3 



Tip of snout to origin of first dorsal 1 3 



Origin of first dor-al to origin of second 1 4 



Length of base of second dorsal 4.5 



Greatest length of pectorals 8 



Length of head on back f 8 



From anterior margin of lower lip to origin of anal 1 10 



Snout to anterior margin of lower lip ... . 3.25 



Greatest circumference at origin of anterior dorsal 1 6 



Mustelus Californicus. Gill. 



This is the common " dog-fish " of San Francisco Bay. It does not usually 

 attain the dimensions of the species last named, and is easily distinguished 

 from that prettily marked species by its plain uniform slaty hue, becoming 

 whitish beneath. 



Semicossyphus pulcher. Gunther. (Labrus pulcher. Ayres.) 



This fish was the first of the sixty-eight Californian species described by Dr. 

 W. 0. Ayres, and its description forms the first page of the first volume of 

 the proceedings of this Academy. The smaller number of spinous rays in 

 dorsal, the presence of a posterior canine tooth, and the absence of scales on 



