Sharks of the Family ycyliorhinidas. 455 



Pectoral Ha extending nearly | of the distance from 

 its ori^'in to that of the pelvics ; end of anal 

 below that of second dorsal 9. ventriosus. 



Pectoral lin extendiiif,' -^ of the distance from its 



origin to tliat of the pelvics 10. umbratilis. 



III. Lower lip not overlapped by the upper ; usually a distinct labial 

 fold at the angle of the mouth. Dorsal fins usually subequal, the 

 first rarely longer than the second ; pelvic fins unt united. Xo 

 nasal cirri. (Halcelurus.) 



A. Length of base of anal more than its distance from the caudal. 



L Aual from a little le.s3 than 2 to nearly 3 times as long as the 

 second dorsal ; dermal denticles on upper surface of tail not 

 enlarged. 



a. Labial fold extending along the lower jaw ^ or a little less 



than ^ of the distance to the symphysis. 

 Anal 2f as long as second dorsal, which is larger 



than the first 11. iiidicus. 



Anal 2h as long as s^^cond dorsal, which is slightly 



larger than the first 12. brunneus. 



Anal more than twice as long as second dorsal, 



which is as large as the first 13. spongiceps. 



Anal twice as long as second dorsal, whicli is as 



large as the first 14. profundorum. 



b. Labial fold extending along the lower jaw ^ the distance to 



the symphysis ; anal nearly twice as long as either dorsal. 



15. analis. 



c. Labial fold extending along the lower jaw ^ the distance to 



the symphysis ; anal twice as long as either dorsal. 



lt>. hispidus. 



2. Anal If as long as second dorsal ; a band of enlarged dermal 



denticles on the upper surface of tail .. 17 . xaniurus. 



3. Anal not much longer than second dorsal ; dermal denticles on 



upper surface of tail not enlarged ; labial fold extending along 

 the lower jaw about J- the distance to the symphysis. 



Second dorsal entirely above the anal 18. cephalus. 



Anal ending below the middle of second dorsal. ... 19. canescens. 



B. Length of base of aual equal to or less than its distance from the 



caudal. 



1. Anterior nasal valves separate from each other and from the 

 mouth. 



a. Labial fold extending along the lower jaw not more than ■ 

 the distance to the symphysis ; anterior nasal valves nearly 

 rectangular. 



a. Snout rounded ; labial fold very .^hort or absent. 



20. buergeri. 

 jS. Snout pointed ; labial fold distinct. 

 Interspace between the nasal valves a little more 

 than 'I the prreoral length of snout ; a short 



labial fold at the angle of the mouth 21. quagga. 



Interspace between the nasal valves not more than 

 I the praeoral length of snout ; a labial fold at 



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