38 THE PLAGIOSTOMIA. 



trils much nearer to the mouth than to the end of the snout. Eye little in 

 advance of the mid length of the mouth. Mouth large, length equal to preoral 

 distance, angles midway from end of snout to pectorals. Teeth large, in 2 ^~ 

 rows; cusp lanceolate, strong, curved, with sharp edges, without basal denticles; 

 base two-rooted, rather swollen; third tooth of the upper jaws much smaller 

 than the second or the fourth. Eye comparatively small. Spiracles minute, 

 above and somewhat behind the angle of the mouth. Width of gill openings 

 nearly equal to preoral length of snout. Pectorals large, falciform, base and 

 inner edge together equal to about half of outer edge, outer angle sharp, hind 

 margin deeply concave. Origin of dorsal nearly above the end of the pectoral 

 base; dorsal base nearly one third of the interdorsal space, and about equal to 

 the distance from the origins of the ventrals. Second dorsal and anal subequal, 

 origin of anal a short distance behind that of the second dorsal. Caudal large, 

 lunate, subcaudal lobe greatly developed, blunted. 



Bluish grey to brown; white beneath. 



Mediterranean and Atlantic. 



ISURUS GLATJCUS. 



Oxyrhina glauca Muller & Henle, 1841, Plagios., p. 69, pi. 29; Schlegel, 1850, Jap. Pisces, p. 302; 



Dumeril, 1865, Elasm., p. 409. 

 Isuropsis glaucus Gill, 1861, Ann. N. Y. lye, 7, p. 398, 409 (name); Johd. & Fowler, 1903, Proc. 



U. S. nat. mus., 26, p. 623. 

 Lamna glauca Giinth., 1870, Cat. fishes Brit, mus., 8, p. 391; 1910, Siidsee fische, 3, p. 484. 

 Lamna spallanzanii Day, 1878, Ind. fishes, p. 722, pi. 186, f. 2. 



Head nearly one fourth of the total length ; crown depressed in a low arch 

 transversely; snout longer than the mouth, subcorneal. Nostrils small, width 

 two fifths of the length of the orbit, nearer to the eye than to the end of the snout. 

 Length of mouth equal its width; sides straight to the broadly arched anterior 

 portion; labial folds nearly half the length of each jaw, at the inner edge of the 

 lips. Teeth long slender, unequal, in §§ rows, sharp-edged, outlines sinuate, 

 without denticles at the sides of the base. Spiracles minute, above the angle of 

 the mouth. Outer edge of pectoral about four times as long as the inner, angles 

 rounded, hind margin slightly concave. Origin of the first dorsal near a vertical 

 from the inner extremity of the pectoral, front margin strongly curved; base 

 about half its length farther back than that of the pectoral, length little greater 

 than the height of the fin, more than one third of its distance from the second 

 dorsal; hind angle rather short but sharp; greater part of hind margin vertical. 

 Second dorsal very small, base almost entirely in front of that of the anal. Anal 



