7. GALEORHINID^E - MUSTELUS. 19' 



sixty species; found in all seas. (Carckariidw part (Carchariina and 

 Mustel'ma) Giinther, viii, 357-380, and 383-388.) 



* Teeth flat and paved, without cusps or cutting edges ; spiracles present. (Muntelince. ) 

 . No pit at the root of the tail; labial folds well developed ......... MUSTELUS 14. 



** Teeth more or less compressed, with entire or serrate sharp edges. (Galeorhinina;.) 

 b. Spiracles present. 

 o. No pit at the root of the tail. 



d. Teeth small, each with a mediaii cusp and one or two small lateral cusps 

 on each side ........................................... TRIACIS, 15. 



dd. Teeth larger, with a single cusp, oblique, notched and serrated, 



GALEORHINUS, 16. 



cc. A pit at the root of the tail ; teeth all serrate ; caudal fin with a double 

 notch ............................................ GALEOCERDO, 17. 



bb. Spiracles obsolete. 



e. Teeth serrate, more or less (entire in the very young or very old) ; little 



oblique or nearly upright. 



/. Teeth well serrated (in the adult) ; those of the upper jaw compara- 

 tively broad or triangular; those of the lower narrow and claviform, 



CARCHARINUS, 18. 



ff. Teeth scarcely serrated, constricted at base, narrow, claviform, and 

 straight in both jaws ........................... ISOGOMPHODOX, 19. 



ee. Teeth all entire. 



ff. Teeth nearly upright, the points not much directed towards the 

 sides ............................................. APRIONODOX, 20. 



gy. Teeth oblique and flat, the points turned to the right or left away 

 from the centre, so that the inner margins are nearly horizontal and 

 present a cutting edge .............................. SCOLIODON, 21. 



14. MUSTEL.US Cuvier, 1817. 



(Hound Sharks.) 

 (Bellon, Cuvier, Regue Animal: type Mustelus vulgar ts M. & H.) 



Body elongate, slender, not elevated ; snout comparatively long and 

 flattened; mouth crescent-shaped, with well-developed labial folds; 

 teeth small, many-rowed, Hat and smooth, rhombic, arranged like pave- 

 ment, alike in both jaws ; eyes large, oblong ; spiracles small, just be- 

 hind the eyes ; pectoral fins large ; first dorsal large, not much behind 

 pectorals; second dorsal somewhat smaller; anal opposite second dorsal 

 and still smaller ; veutrals well developed ; basal lobe of caudal almost 

 obsolete ; embryo not attached to uterus by a placenta. Small sharks, 

 the smallest of the American species, known at once by the smooth, 

 paved teeth. (Latin, mwttela, a weasel or martin ; the use of the word 

 similar to that of 



19. in. hi mi ii 9 us (Blainv.) J. & G. Smooth Hniniil ; Dor/ SJiai-l: Emis&ole. 



Body slender, tapering backward from the dorsal fin to the long 

 slender tail ; snout depressed, moderately sharp ; mouth small, the teeth 

 all alike, a fold at the angle of the mouth ; first dorsal rather large, 



