58 LIST OF FISH. 



4. Mcstelus megalopterus. Large-finned Hound-fish. 



Mustelus megalopterus, Smith, Illustr. Afr. Zool. pi. 11 (male)), 



1839. 

 Hah. — Cape Seas, 



II. Nictitating membranes none ; spiracles distinct, often small. 



A. Dorsal-fins two ; anal distinct. 



Squali (§ 2, c), Mull. $■ Henle, Mag. Nat. Hist. ii. 1838. Plagiost. 

 67. 



6. The gill-openings are large, and all lie hefore the breast-fins. 

 The eye-openings roundish. The second back-fin and the anal 

 roundish, of equal size, opposite to one another. Distinct tail-pits. 

 Crescentic tail-fin. A keel on each side of the tail. Spiracles very 

 small. Gut-valve screw-formed. — Isurina. 



Lamnoidia, Midi. 8,- Henle, Mag. Nat. Hist. ii. 1838. Plagiost. 67. 

 Lamnae, Mull. $r Henle, Plag. 67. 

 Lamnini, Bonap. Selac. Tab. Anal. 9, 1838. 



1. ISURUS. 



Snout three-sided, pyramidal, pointed. Nasal-flap short, three- 

 sided. Spiracles very small, far behind the eyes. Teeth flat, not 

 serrated, three-sided, with a short-pointed denticle on each side of 

 the base of the older ones, which is sometimes doubled. The jaw 

 end of the teeth is deeply concave towards the jaw. No middle 

 teeth, but a space in their stead in the upper and under-jaw. The 

 two front teeth of the upper-jaw are followed on either side by one 

 or more smaller ones. The skin is smooth. Scales very small. 



Isurus, Rafin. Caratt. 



Lamia, Greeks. Risso, Ichth. Nice, (not Fab.). 



Lamna, Cuv. Reg. An. 2 ed. ii. 388, 1817. Mull. <$• Henle, Mag. 



Nat. Hist. ii. 1838. Plagiost. 67. 

 Carcharhinus, sp., Blainv. Bull. Soc. Phil. 121, 1816. 



1. Isubtjs cornubicus. The Porbeagle. 



Canis carcharias, Aldrov. 383. 



Porbeagle, Borl. Cornw. 265, t. 26, f. 4. Yarr. Brit. Fish. 384. 



