Sharks of the Family Squalidse. 45 



7. Spinax lucifer^ 



Etmopterus heifer, Jord. & Snyder, Proc. U.S. Nat. Mus. xxv. 1902, 

 p. 79; Jord. & Fowler, ibid. xxvi. 1903, p. 634, fig. 5. 



Hah. Japan. 



In the British Museum four specimens, 280 to 320 mm. in 

 total length. 



5. Squalus. 



Squalus (part.), Linn. Sysfc. Nat. ed. 10, p. 233 (1758). 

 Squalus, Rafin. Caratt. p. 13 (1810). 

 Acanthorhinus, Blainv. Journ. Phys. 1816, p. 263. 

 Acanthias, Risso, Ear. Merid. Hi. p. 131 (1826). 

 Entoxychirus, Gill, Proc. Ac. Philad. 1862, p. 490. 



Eight species. 



Synopsis of the Species. 



I. Dorsal fin-spines without grooves or ridges ; lower lobe of caudal 

 fin without posterior notch; snout obtusely or acutely pointed. 

 {Squalus.) 



A. Nasal valves simple, triangular ; back and sides with scattered 



rounded or oblong pale spots, which may disappear in large 

 specimens. 



1. Pectoral fin, when laid back, extending to the vertical from 



first dorsal spine, or a little beyond. 

 Praeoral length of snout not greater than the distance 



from eye to first gill-opening 1. fernandinus. 



Prseoral length of snout greater than the distance from 



eye to first gill-opening 2. acanthias. 



2. Pectoral fin, when laid back, extending to below the middle of 



first dorsal fin 3. sucklii. 



B. Nasal valves more or less distinctly bilobed ; no spots on the 



body. 



1. Free edge of pectoral fin straight or slightly emarginate, poste- 



rior angle not acutely pointed. 

 Pectoral fin, when laid back, extending to below the 



middle or posterior part of the base of the first 



dorsal fin 4. mitsukurii. 



Pectoral fin, when laid back, extending to the vertical 



from the posterior end of base of first dorsal fin . . 5. blainvittii. 

 Pectoral fin, when laid back, extending well beyond 



the posterior end of base of first dorsal fin 6. acutijrinnis. 



2. Free edge of pectoral fin distinctly emarginate ; posterior angle 



acutely pointed 7. megedops. 



II. Eacb dorsal fin-spine with a prominent anterior ridge with a groove 

 on each side of it ; lower lobe of caudal fin with a posterior notch ; 

 snout rounded ; posterior angle of pectoral fin considerably pro- 

 duced and acutely pointed. (Entoxychirus.') . . 8. uyatus. 



