262 



BUI.I.ETIN OF THE BUREAU OF FISHERIES. 



Denticles. — The dermal denticles are large, subequal, slightly imbricated, ovate in outline, with a 

 high, arched median keel, and a deep channel on each side of keel; lateral margins curved outward, 

 upturned edges sometimes thickened, keellike, outer edge truncate, or with a narrow basal winglike 

 expansion; apical margin pointed, acute-angled; pedicel broad, little more than a constriction of outer 

 denticle, resting on a large rhomboidal basal plate. Description of specimens 264.2 to 365.8 cm. long. 

 In an example igS.i cm. long the denticles were smaller, unequal, rather widely separated, without or 

 with only slightly upturned lateral margins. 



Measurements of an Example (No. i) 198. i Cm. {6y^ Feet) Long from Menemsha Bight 

 Mass., Taken Aug. 13, 1913, and One (No. 2) 279.4 Cm. (9 Feet 2 Inches) Long from 

 Beaufort, N. C, Taken Aug. 8, 1914. 



No. 3. 



Tip of snout to — 



Base of dorsal 



Anterior margin of eye 



First gill slit (upper angle) 



Last gill slit (upper angle) 



Base of pectoral 



Front of mouth 



Outer angle of nostrils 



Spiracle 



Horizontal diameter of orbit 



Length of aperture of nostrils 



Distance between nostrils 



Distance between angles of mouth 



Height of— 



First gill slit 



Second 



Third 



Fourth 



Fifth 



Length of anterior margin of first dorsal 



Length of posterior margin of first dorsal 



Base of first dorsal 



Distance between dorsals 



Anterior margin of second dorsal 



Posterior margin of second dorsal 



Base of second dorsal 



Distance from second dorsal to base of caudal. . 



Length of anterior margin of pectoral 



Length of posterior margin of pectoral 



Breadth of pectorals 



Axil of pectorals to origin of ventrals 



Anterior margin of ventrals 



Distal margin of ventrals 



Posterior margin of ventrals 



Distance between axil of ventrals and anal. . . . 



Anterior margin of anal 



Posterior margin of anal 



Base of anal 



Length of upper caudal lobe 



Length of subcaudal lobe 



Breadth of distal margin of caudal tip 



Tip of caudal to notch 



cm. 



56.0 



12. S 



29.6 



37-4 



35-0 



8.3 



7-5 



17-9 



2-7 



2.g 



8.1 

 IS' 7 



4-S 

 4.8 

 5-0 

 S-3 

 3-9 



19.0 

 9.2 



14.4 



14.0 

 8.8 

 IS- 1 



55° 

 19- S 

 2-5 

 9-S 



cm. 



80. a 



48.0 



3-S 

 4-0 



28.0 

 16.0 

 22.0 

 70.0 

 II. o 

 13- o 

 12.0 



22.0 

 41.0 

 14.0 

 2S-0 

 79.0 

 14- o 



16. s 

 9.0 

 19.0 

 17.0 

 10. o 



17.0 

 76.0 



28.5 



Head short, broad, very blunt and robust; snout short, depressed, semicircular; eye large, lateral, 

 above middle of sides of mouth, nictitating membrane present, highest anteriorly; mouth large, nearly 

 semicircular, near tip of snout; angles with a distinct labial fold above and below; distance between 

 angles nearly equal to their distance from tip of snout; nostrils widely separated, length of aperture 

 nearly one-third of their distance apart, anterior margin with a prominent lobe; spiracle small, about 

 an eye diameter behind eye, in line with its upper margin; body slender, tapering posteriorly to a very 

 slender caudal pedtmcle; a distinct ridge along median line of back between dorsals; caudal peduncle 

 depressed, angled laterally. 



Origin of first dorsal above tip of lower pectoral lobe, fin small, high, anterior lobe slightly rounded, 

 posterior lobe long, acuminate; distal margin concave, slightly sinuous; base of fin nearly equal to its 

 height; second dorsal resembling the first, anterior lobe more rounded; pectorals small, falcate, tips 

 barely reaching to posterior base of first dorsal ; ventrals truncate ; anal origin slightly behind origin 

 of second dorsal, anterior lobe acute, sickle-shaped, posterior lobe acuminate, distal margin very deeply 

 incised; caudal elongate, about 3.7 in total length, upper lobe very narrow, subcaudal lobe narrow, 

 elongate. 



