On the Sharks of the Family Squalidse. 39 



EXPLANATION OF PLATE V. 



Fiy. 1. Atyloides aucklandicus, sp. n. First gnathopod. 



Fiy. 2. Ditto, young. First gnathopod. 



Fig. 3. Aucklandia enderbyi, sp. n. First gnathopod. 



Fig. 4. Ditto. Second gnathopod. 



Fig. 5. Hyale trigonochir, sp. n. First gnathopod, male. 



Fiy. 6. Ditto. Second gnathopod, male. 



Fiy. 7. Ditto. Second gnathopod, female. 



VII. — A Synopsis of the Sharks of the Family iSqualidae. 

 By C. Tate Regan, M.A. 



The Squalidas may be diagnosed as sharks without an anal 

 fin, with five or six gill-openings on each side, the last in 

 front of the base of the pectoral fin, which is normally shaped, 

 and with the mouth inferior. 



Fourteen genera may be recognized. 



Synopsis of the Genera. 



I. Snout normal, not produced into a saw-like rostrum. (Squalince.) 



A. Mouth crescentic. 



Each dorsal tin preceded by a spine 1. Centroscy Ilium. 



No fin-spines 2. Echinorhinus. 



B. Mouth transverse, but little arched, with a straight oblique 



groove on each side. 



1. Mouth rather small; body trihedral, the flat lower surface 



margined on each side by a strong dermal fold ; dorsal fin- 

 spines present 3. Oxynotus. 



2. Mouth wide ; body elongate, subcylindrical. 



a. Each dorsal fin preceded by a spine, which may project or 

 may be small and concealed. 



Teeth in the upper jaw erect, tricuspid or penta- 



cuspid ; lower teeth oblique, unicuspid, with 



points strongly deflected laterally 4. Spinax. 



Teeth in both jaws oblique, unicuspid, with points 



strongly deflected laterally 5. Squalus. 



Upper teeth erect, lanceolate, two-rooted ; lower 



teeth erect, triangular 6. Scymnodon. 



Upper teeth erect, lanceolate, two-rooted ; lower 



teeth oblique, with points deflected laterally . . 7. Centroscymnus, 

 Upper teeth erect or somewhat oblique, triangular, 



with quadrate bases ; lower teeth oblique, with 



points deflected laterally 8 Centrophorus. 



