62 COPEIA 



ter knowledge of their distribution and comparative 

 abundance. At present we know only that Mustelus 

 californicus is reported from San Francisco to the 

 Gulf of California, but whether both species are in- 

 cluded in this range, or whether Mustelus henlei is 

 the commoner form in the northern part of it is un- 

 certain. 



Garman ( Mem. Mus. Comp. Zool. XXXVI ) , 

 distinguishes Mustelus lienlei and presents a very 

 good plate of it, but he does not separate it very well 

 from Mustelus californicus. 



I recently rather hastily examined Gill's type at 

 the National Museum — a young specimen nine and 

 a half inches in length, with the umbilical scar 

 rather fresh, and compared it with the young of Mus- 

 telus californicus of similar size. I concluded that 

 they were very doubtfully separable. Since then, 

 however, I have had occasion to examine all of the 

 adult specimens at Stanford University that I had 

 supposed were referrable to Mustelus californicus, 

 and have found both of these species represented and 

 rather easily separated. 



In Mustelus henlci the base of the anal is even 

 with, or only slightly posterior to, the base of the 

 second dorsal. In Mustelus californicus the anal is 

 behind the second dorsal, a distance nearly or quite 

 equal to the long diameter of the eye. 



In Mustelus henlci the dorsal is more ante- 

 riorly placed. The distance from its origin to the 

 last gill opening is equal to the length of the snout, 

 while in Mustelus californicus this distance is equal 

 to two-thirds or three-fourths of the length of the 

 head. 



In Mustelus henlci the tips of the pectorals when 

 laid close to the body reach at least to opposite the 

 middle of the dorsal base, while in Mustelus californi- 

 cus they scarcely reach to under the anterior fourth 

 of the dorsal base. 



