CARCHARIIDvE. 289 



Family I— CARCHAMID^E. 



The snout may be produced longitudinally (Carchariidce, "true sharks") or 

 laterally (Zygcenina, "hammer-headed sharks"). Spiracles absent or present. 

 Eye with a nictitating membrane. A small pit may or may not exist above the 

 root of the tail, and a groove behind the angle of the mouth may be present 

 or absent. Mouth crescentic, inferior. Teeth may be erect or oblique, with a 

 single cusp, having sharp and smooth or serrated edges : or they may be small, 

 the cusps being obsolete : or with one in the centre and one or two lateral ones : 

 or even obtuse. The first dorsal fin, destitute of a spine, is placed opposite the 

 interspace between the pectoral and ventral : anal fin present. 



The fishes belonging to this family, which are found in British "waters, are 

 confined to the following genera : — 



I. Carcliarias. — No spiracle. Teeth with a single cusp. Snout longitudinally 

 produced. A pit at the root of the tail. 



II. Galeus. — Small spiracles. Teeth with a single cusp. Snout longitudinally 

 produced. No pit at the root of the tail (p. 292). 



III. Zygoma. — No spiracles. Teeth with a single cusp. Snout laterally 

 produced. Nostrils on the front edge of the head. A pit at the root of the 

 tail (p. 294). 



IV. Mustelus. — Spiracles small. Teeth obtuse. Upper lip well developed. 

 No pit at the root of the tail (p. 295). 



Genus I — Carchaeias, Miill. and Hevle. 



No spiracles. A pit before the root of the caudal fin. Snout longitudinally 

 produced. Mouth crescentic : the labial fold or groove rarely extends beyond the 

 angle of the mouth. Teeth with a sharp triangular cusp, sometimes dilated. The 

 first dorsal fin, destitute of a spine, is placed opposite the interspace between the 

 pectoral and ventral : caudal with a distinct lower lobe. 



The genus has been divided as follows : — 



Teeth in the jaws entire without swollen bases, Scoliodon, or with them, 

 Physodon : or the bases of upper teeth serrated, Aprionodon. Some or all the teeth 

 serrated, as the base of the upper ones, Hypoprion, or the base and cusps, 

 Prionodon. 



Although the white shark, Carcliarias lamia, has been admitted into works on 

 British fishes, evidence is deficient that it has been taken off our coasts. Grew, in 

 his " Rarities of Gresham College," p. 90, remarked that it is sometimes found on 

 the Cornish coast ; Low, on hearsay, that it was found off the Orkneys, but no 

 descriptions appear to be extant from a British specimen. I have, therefore, 

 omitted it. 



1. Carcharias glaucus, Plate CLII. 



Qaleus glaucus, Rondel, p. 378; Gesner, De Aquat. p. G09; Aldrov. p. 394; 

 Willughby, lil>. 3, cap. ii, t. B 8, p. 49; Ray, Synop. Piscium, p. 20. Squalus, 

 sp. Artedi. Synon. p. 98. no. 13, and Gen. p. 69, no. 13. Blue shark, Watson, 



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