12 CALIFORNIA ACADEMY OF SCIENCES 



Teeth in upper jaw broadly triangular, oblique, the anterior edt;e gently convex, the inner 

 gently concave and often with a slight notch dividing the margin into equal parts. Teeth in lower 

 jaw erect, narrowly lanceolate from a broad base. All the teeth are strongly serrate on both margins. 



Pectorals long and wide, concave posteriorly, hence appearing falcate, their tips extending 

 slightly beyond base of first dorsal. Both angles are broadly rounded. Upper margin of pectorals 

 3^ to 3^ times lower margin, and i^ to i^ times the posterior margin; its length equals that of head 

 in advance of first gill-slit. A line joining a.xil of pectorals passes in front of origin of first dorsal a 

 distance equaling diameter of orbit. Base of first dorsal contained i-| to li times in anterior margin 

 of fin, and if or i| times in the interspace between dorsals. Upper margin concave, the posterior but 

 little produced, contained 3| to 3| times in anterior margin. Second dorsal inserted well in advance 

 of anal, the length of its base contained 2i to 2| times in base of first dorsal, 4|^ to 4| times in the 

 interspace, if to i^ times in its distance from front of caudal pit. Posterior lobe of second dorsal 

 extends nearly half-way to origin of upper caudal lobe. Front of anal under end of first third of 

 dorsal base, the two fins nearly equal in length, the anal perhaps slightly the longer. Margin of anal 

 much more deeply concave. Distance from anal to origin of lower caudal lobe contained i^ times in 

 distance from second dorsal to origin of upper caudal lobe. Caudal slightly exceeding ^ the total 

 length; the lower lobe with rounded angle appearing bluntly falcate, contained 2^ times in upper lobe. 



Color uniform light blue or bluish gray above, white below. Caudal and second dorsal black 

 margined; the lower caudal lobe and distal half of pectoral largely blackish. 



TliLs species is well known though not abundant at Panama, aiul is more highly 

 prized as food than other sharks. It appeared in the market on two occasions during 

 the stay of the expedition, and three specimens were preserved, measuring from 92 

 to 95 cm. Two of these are males with the claspers quite undevelojied, not nearly 

 reaching margin of ventrals. The species is said to reach a large size. 



C. azureus is extremely near C. nicaragven^is, from Lake Nicaragua and its 

 outlet, the San Juan River. Dr. Jordan has kindly compared the above description 

 with a specimen of O. nicnraguensis (No. 89913) in the United '.States National 

 Museum. The latter has a longer and wider snout, the length of which is contained 

 11 in its preoral jjortion, its width opposite the nostrils equaling the distance fi'om 

 the angle of the mouth to the third gill-slit. The base of the first dorsal is I the 

 interspace between dorsals, and the base of the second dorsal is contained 21 times 

 in the first. The lower caudal lobe is contained 2| in the upper lobe. The pectoral 

 is but faintly dusky. These differences are not great, Init there has been no 

 opportunity to make a direct comparison. In view of the exceptional distribution 

 of C. nicurayuensis, known only from fresh waters, which l)elong to the Atlantic 

 slope, it has not been thought wise to make the identification. 



9. Scoliodon longurio Jordan I- Gilbert. 



Abundant at Panama, where six specimens were obtained. The Ifugth of the 

 base of the first donsal is contained 21 to nearly 3 times in the interspace between 

 dorsals, not 2j times, as stated by Jordan & Evermann (1890, p. 42). The teeth 

 are not at all serrate in the Panama specimens; the thin margin is sometimes gently 

 sinuate, but never toothed. 



