ACADEMY OF SCIENCES. 85 



Numerous specimens of this species caught in Magdalena Bay have been 



examined by us, and careful comparison with the forms described in Gun- 



ther's catalogue has led me to the conclusion that this is a new species. From 



A. vomer it differs in the extreme shortness of its ventrals, none of the rays 



of which, or of the spinous dorsal, are continued into filiform prolongations; 



also, in the greater proportional length of the pectorals. From A. setapinnis 



it can be at once distinguished by the prolongation of the first rays of the 



soft dorsal and the anal. 



The dimensions of a large specimen are as follows: 



Inches. 



Extreme length in straight line from the tip of lower jaw to tip of lower 



lobe of tail 15.5 



Extreme height in front of anal fin 7.2 



Height immediately behind eye 6.65 



Greatest girth 14.60 



Length along profile from tip of lower jaw to origin of soft dorsal 10.60, 



Length from tip of lower jaw to origin of anal 6.75 



Length of base of soft dorsal 5.60 



Length of base of anal 5.50 



Length of base of pectorals 62 



Length of head above orbit 3 



Length of pectorals 5.45 



Length of ventrals 5 



Length of caudal to division of lobes 2.25 



Length of lower lobe of caudal from fork , 3.40 



Length of upper lobe of caudal from fork 2.95 



Length of longest ray of dorsal 4.10 



Length of longest ray of anal 3 



Length of lower jaw 1.8 



Distance from tip of lower jaw to orbit 2.65 



Diameter of orbit 75 



Greatest thickness of fish /. 1 



One or two specimens exceeded these dimensions. 



Cestracion francisi. Grd. U. S. P. R. R. Rep., vol. x, p. 365. 



Of this genus of sharks, so interesting from its occurrence in geological 

 time as far back as the Devonian Age, only four species now exist; one of 

 these, C. phUlipi, is the often-mentioned Port Jackson shark; another, C. 

 francisi, has been caught in the Bay of Monterey, and occurs along the coast 

 at least as far south as Magdalena Bay, Lower California, from which place 

 we received a single fine specimen, the dimensions of which are appended : 



Ft. In. 



Length from tip of snout to tip of caudal 2 6% 



Length from tip of snout to origin of first dorsal 8% 



Length from origin of first dorsal to origin of second dorsal. . . 8% 



Circumference immediately in front of first gill-opening 1 1% 



Circumference immediately in front of pectorals 1 1% 



