FISHES OF THE PHILIPPINE ISLANDS AND ADJACENT SEAS 223 



Family SQUALIDAE 



Body usually elongate, partly rounded. Tail slender, compressed. 

 Head depressed. Eyes lateral, without nictitating membrane. Mouth 

 inferior, rather large, moderately arched, with deep labial folds and 

 deej) groove at each angle, slightly protrusible. Teeth compressed, 

 variously formed, oblique, erect, with one or more cusps. Nostrils 

 inferior, separate, remote and not joined with mouth. Gill openings 

 moderate or narrow, all before pectorals. Spiracles rather large 

 Dorsal fins 2, each with spine in front, first dorsal before ventrals. 

 No anal. Lower caudal lobe small or obsolete. Ventrals inserted 

 posteriorly, not much before second dorsal. 



Small sharks, mostly of cool or temperate seas or deep water. 

 The more typical genera usually known by the presence of a strong 

 spine at the front of each dorsal fin. Many are gregarious. Many 

 fragments as fossils, usually as teeth or spines, all from late Tertiary 

 deposits. 



ANALYSIS OF GENERA 



a\ Etmoptekinak. Dorsal spines with lateral grooves ; notch below terminal 

 part of caudal. 

 6'. Teeth unicuspid, unlike in 2 jaws ; nostrils oblique. 

 c\ Inner pectoral angles not extended ; nostrils oblique. 



(Z\ Scale crowns pinacoid, rounded, excavated or smooth, on slender 



peduncles Centroscymnus 



d^. Scales pedunculate, with 3 strong, extended keels Scymnodon 



c^ Inner pectoral angles not or scarcely extended ; nostrils transverse. 



e\ Scales leaf-shaped, stalked, with strong median keel_ Centrophorus 

 e'. Scales tricuspid, tridigitate, slender in stalk and cusp ; snout much 



produced Deania 



c'. Inner pectoral angles extended; scales subsessile, with converging keels 



and stout peduncle Entoxychinis 



6'. Teeth pluricuspid ; nostrils slightly oblique. 



f. Teeth pluricuspid only in upper jaws Etmopterus 



f. Teeth pluricuspid in both jaws Centroscyllium 



a*. Dorsal spines without lateral grooves; caudal not notched subterminally 

 below. 



(f. Squalinae. Body subrounded ; dermal folds on tail, if present ; 



teeth alike in both jaws Squalus 



g^. OxYNOTiNAE. Body subtriangular, dermal fold each side ; teeth 

 unlike in 2 jaws; first dorsal spine inclined forward. 



Oxynotus 

 Genus CENTROSCYMNUS Bocage and Capello 



Centroscymnus Bocage and Capello, Proc. Zool. Soc. London, 1864, p. 263. 

 (Type, Centroscymnus coelolepis Bocage, monotypic.) 



Body partly fusiform, slightly compressed. Snout produced. Eye 

 large, with nictitating membrane, pupil circular. Mouth transverse, 

 slightly curved, deep groove and labial fold at each angle. Teeth 

 unlike in 2 jaws; upper raptorial, small, lanceolate, in 3 groups, 



