264 



BULLETIN OF THE BUREAU OF FISHERIES. 



^6 

 in ^^ rows, cusps long, pointed, basal shoulder on posterior margin prominent, cutting edges distinctly 



serrate; teeth at symphysis erect, or nearly so, with a distinct shoulder on each side of cusp. 



Denticles. — The dermal denticles vary in form of sculptiu-ing with age, three-keeled in the young, 

 five-keeled in older examples. In a specimen 52.3 cm. long the denticles are very small, being about 

 0.17 mm, long by 0.16 mm. broad, closely imbricated, normally three-keeled (3 to 5); apical margin 

 normally five-lobed (3 to 5), lobes long, narrow, sharp-pointed; pedicel short and heav^', resting on a 



Fig. 17. — Denticles. Cestracton zygesna, 52.3 cm. long, from Beaufort, N. C. 



large rhomboidal base. In an example 124.5 ^^- ^"^"S they are five-keeled; with or without lobed 

 apical margin. 



Measurements of a Male 124.5 Cm. (49 Inches) Long, Taken in the Pound Net, July ii, 1914. 



Breadth of head 35.0 



Width of hammer 10. o 



Tip of snout to — 



Origin of first dorsal 35.0 



First gill slit 21.0 



Last gill sUt 28. 8 



Base of pectoral 26-0 



Front of mouth 7.0 



Depth of body at origin of first dorsal 17.0 



Horizontal diameter of orbit 2.5 



Length of nasal aperture 2. 5 



Distance between angles of mouth 8. s 



Height of— 



First gill slit 4-o 



Second g:ill slit 4-0 



Third gill slit 4-5 



Fourth gill slit 4.0 



Fifth gill slit 3.0 



Length of anterior margin of first dorsal 20. o 



Length of posterior margin of first dorsal 5.5 



Base of first dorsal 19-5 



Distance between dorsals 29. s 



Length of anterior margin of second dorsal 5.0 



Length of posterior margin of second dorsal 7.5 



Base of second dorsal 5.0 



Distance from second dorsal to caudal base 9.0 



Length of outer margin of pectorals 16. 5 



Length of inner margin of pectorals 6. s 



Breadth of distal margin of pectorals 15.0 



Axil of pectorals to origin of ventrals 23.5 



Length of outer margin of ventrals 9. o 



Length of inner margin of ventrals 3.5 



Breadth of distal margin of ventrals 9.0 



Length of claspers 4. s 



Distance between base of ventrals and anal 10. s 



Length of anterior margin of anal 7.0 



Length of posterior margin of anal 5.0 



Length of base of anal 6. s 



Posterior base of anal to caudal 9-0 



Length of upper caudal lobe 39. 5 



Length of subcaudal lobe 15. o 



Tip of caudal to notch 8> a 



Dorsal very high, anterior margin nearly straight; distal margin sinuous, markedly concave basally, 

 lower lobe short, acuminate, origin of fin over axil of pectoral; second dorsal small, its origin over anterior 



