164 University of California Publications. [Zoology 



from 314 to 3%. The distance from the insertion of the ventral 

 to a point vertical from the insertion of the first dorsal is from 

 61/2 to 7% in the body, while in C. lunulatus this distance is from 

 5% to 6%. The vertical from the middle of the first dorsal falls 

 nearer the ventral than the pectoral in M. calif ornicus, and mid- 

 way between these points in C. lunulatus. The anterior margin 

 of the first dorsal when laid close to the back does not reach the 

 posterior tip of the dorsal by a distance equal to the diameter of 

 the eye. In C. lunulatus it does not reach the same point by half 

 the eye. 



The male of M. calif ornicus has a longer, sharper snout than 

 the female, and the distance between the angles of the mouth is 

 le&s. Occasionally these sexual differences do not appear, but 

 they are usually very evident. The individual variation in out- 

 line of snout is great in both male and female, ranging from a 

 continuous blunt curve to a decided angle, approaching, but not 

 invading, the range of variation of C. lunulatus. 



The above measurements were drawn from about sixty speci- 

 mens of M. californicus, and five specimens of C. lunulatus. 



This shark has been noticed as far north as San Francisco by 

 Jordan and Gilbert (1880, p. 458). It is rare northward. 



6. Rhinotriacis henlei Gill. 

 (Jordan and Evermann, 1896, I, p. 31.) 



This shark has been once taken in San Diego Bay by Dr. C. H. 

 Eigenmann (1892, p. 133). It is apparently more common north- 

 ward than has hitherto been supposed, as about fifty specimens 

 were recently sent from the San Francisco markets to Stanford 

 University for dissecting purposes. The species has doubtless 

 been passed over as Mustelus californicus Gill, which it much 

 resembles. It may be known at once, however, by the sharper, 

 cusp-bearing teeth. It has been recorded at Humboldt Bay by 

 Jordan and Gilbert (1881, p. 31). 



The type of the species had probably been born but a short 

 time when collected, as an example taken from the oviduct of one 

 of our specimens is of the same size, 91/0 inches in length, and 

 agrees very well with the original description (Gill, 1862a, p. 



