PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 107 



niiuule pores, these formiug an elliptical area on the lower side of snout, 

 outside of which on each side is a crescent-shaped area of pores. 



Insertion of first dorsal well behind pectoral, but much nearer to pec- 

 toral than ventral; its distance behind posterior base of pectoral Ij in 

 preoral part of snout. 



Anterior lobe of dorsal, when depressed, not reaching the tip of tlie 

 posterior lobe; the distance to the base of posterior lobe from ventrals 

 nearly half preoral part of snout. 



Length of base of first dorsal about equal to the height of the fin, or 

 to the interorbital width, about one-third the distance between dorsals, 

 which is 10 times base of second dorsal. 



Second dorsal very small, its free margin scarcely concave ; the pointed 

 posterior lobe nearly twice the anterior. 



Caudal, 4J in total length; its lower lobe bluntish, about | the up])er; 

 length of caudal equal to distance from snout to base of pectoral. 



Anal fin small, but considerably larger than second dorsal, inserted 

 in front of the latter, so that its posterior part is below the insertion of 

 the dorsal. Length of anal about equal to its elongate posterior lobe, 

 and less than half its distance from the ventrals. Ventrals moderate, 

 their anterior margins two-thirds distance between angles of mouth. 



Pectorals rather small, not quite reaching middle of first dorsal, their 

 tips bluntish, the length of the anterior margin If times interorbital 

 width and 1^ times the free margin. Pectoral scarcely more than one- 

 eighth the total length of the fish. 



Color slaty-gray with a distinct bluish tinge ; white below; upper edge 

 of tail and tip of caudal dusky ; vertical fins faintly margined with 

 dark. 



This species is common in the harbor of Mazatlan, where five s])eci- 

 mens were obtained ; the largest of these (28330), a male, 32 inches long, 

 is apparently nearly matnre, the claspers reaching the anal. It has 

 especially served for the basis of the above description. 



Our specimens agree in most respects with Professor Poey's accounts 

 of his Scolioflon porosns from Cuba. If the generic value of the group 

 called Scoliodon be not admitted, the latter species must receive a new 

 name, as there is already a Cnrcharias porosKs Eanzani. 



Carcharias, sp. incog. 



The jaws of a large shark were obtained at Mazatlan, the species of 

 which we have not been able to ascertain. The following is a descrip- 

 tion of the teeth : 



Teeth |f. Teeth of the upper jaw rather narrowly triangular, the tip 

 rather strongly curved outward;' the inner margin rather strongly con- 

 vex, the outer rather strongly concave; the outer margin with a broad, 

 shallow basal angle, a continuation of the curve of the outer edge of the 

 tooth. Both margins of the teeth strongly serrate, the senxe stronger 



