146 THE PLAGIOSTOMIA. 



edge, each tooth curved outward to present the inner edge for the vertical cutting, 

 both edges strongly serrated; median tooth smaller, asymmetrical, hooked. 

 Teeth less curved in young. Gill openings five, subequal, width twice that of the 

 eye, hindmost two above the pectoral. Pectorals long, reaching the dorsal, 

 narrow, pointed, inner angle short, rounded. Dorsal entirely in front of mid 

 length, longer than high, hind angle acute, base about two thirds as long as the 

 snout, equal to one third of the distance from the second dorsal. Second dorsal 

 little smaller than the anal, base nearly half as long as that of the first dorsal 

 and above that of the anal but extended a trifle farther backward, hind angle 

 much produced. Yentrals small, half as large as the first dorsal, nearly straight 

 on the hind margins. Anal small, base more than half its distance from the 

 caudal, hind margin deeply notched, hind angle acute. Tail slender, caudal fins 

 moderate, acuminate at the end, subcaudal lobe produced, acute, fin narrowed 

 backward. 



Back dark blue or bluish black; whitish below. 



Specimen described from Japan, secured by Mr. Alan Owston. Total 

 length 54, snout to abdominal pores 30, snout to fifth gill aperture 12g, and snout 

 to mouth 5 inches. Specimen figured, on Plate 3, much larger, from Massa- 

 chusetts Bay, secured by Prof. L. Agassiz. 



Thalassorhinus. 



Thalassorhinus Muller & Henle, 1841, Plagios., p. 62. 



Trunk elongate, fusiform; head depressed. Mouth large greatly arched. 

 Teeth subtriangular, denticulate. Nasal valve short. Eye moderate, with a 

 nictitating membrane, pupil vertical. Spiracle medium. Caudal as in Galeus, 

 a notch behind the subcaudal, a caudal pit above and another below. 



Snout rather pointed 



anal exactly below the second dorsal . . . rondeletii (page 146) 

 Snout broad, rounded at the end 



anal below the end of the second dorsal . platyrhynchus (page 147) 



Thalassorhinus rondeletii. 



Squalus rondeletii Risso, 1810, Ichth. Nice, p. 27. 



Carcharias rondeletii Risso, 182G, Hist, nat., 3, Poissons, p. 120. 



Thalassorhinus vulpecula Muller & Henle, 1841, Plagios., p. 02; DumiSril, 18G5, Elasm., p. 396; 



Gunth., 1870, Cat. fishes Brit, mus., 8, p. 378. 

 Thalassorhinus rondeletii Gray, 1851, Cliondropterygii, p. 55; Doderlein, 1881, Man. ittiol. Medit., 



2, p. 38. 

 Thalassinus rondeletii, Moreau, 1881, Poiss. France, p. 319. 



