36 THE PLAGIOSTOMIA. 



ISURUS PUNCTATUS. 



Plate 6, fig. 4-6; Plate 56, fig. 5, (heart); Plate 58, fig. 3, (intestine); Plate 62, 63, (skeleton). 



Lamna punctata Storer, 1839, Report fishes, p. 1S.5, pi. 3, f. 2; Boston journ. nat. hist., 2, p. 534; 1846, 



Mem. Anier. acad., new ser., 2, p. 504; 1867, Mass. fishes, p. 249, pi. 37, f. 1 (non syn.). 

 Oxyrhina dekayi Gill, 1861, Proc. Acad. nat. sci. Phila., p. 60 extra. 

 Isuropsis glaucus Gill, 1864, Proc. Acad. nat. sci., Phil., p. 260. 

 Oxyrhina punctata Dumeril, 1865, Elasm., p. 409. 



Lamna cornubica Jordan & Gilbert, 1883, Bull. 16, U. S. nat. mus., p. 30. 

 Isurus punctatus Garman, 1888, Bull. M. C. Z., 17, p. 79, pi. 1. 



Form similar to that of /. nasus. Body subfusiform, massive in the anterior 

 half, depressed and with lateral keels in the caudal peduncle. Head slightly 

 flattened on the crown, snout long, pointed, conical. Nostrils small, far apart, 

 near the mouth and the eyes. Eye large, orbit round, pupil erect; no nictitating 

 membrane. Mouth large, crescentic ; upper labial fold less than half as long as 

 the jaw, lower much the shorter. Teeth rather small, in || rows, with slender 

 sharp-edged cusp and broad two-rooted base, without denticles at the sides, 

 lower teeth more erect. Spiracles minute, above the angle of the mouth. Width 

 of gill openings less than length of snout. Pectorals subfalciform, width not 

 more than half the length, angles rounded, outer extremity reaching beyond the 

 base of the dorsal. Dorsal in front of the mid length, origin slightly behind the 

 base of the pectoral, greatest length little more than the height, upper angle 

 rounded. Second dorsal very small, above the anal. Anal little larger than 

 second dorsal and origin very little farther forward. Ventrals below the middle 

 of the space between the dorsals, caudal about one fifth of the total length, 

 vertebral axis much raised backward. Spiral intestine with about 38 turns. 



Dark bluish brown on back and sides, abruptly changing to white on the 

 lower surfaces; dorsals, pectorals, and caudal tipped with black. In the axil on 

 the base of the pectoral there is a black area, followed on the fin and the body 

 by a white space as in Carcharodon carcharias. A large spot of black below the 

 outer half of the pectoral. 



Abundant off the eastern coast of the United States. 



ISURUS TIGRIS. 



Lamna punctata DeKay, 1842, N. Y. fish., p. 352, pi. 63, f. 206 (non L. punctata Storer, 1839). 

 Isuropsis dekayi Gill, 1861, Ann. N. Y. lye, 7, p. 409 (non Oxyrhina dekayi Gill, 1861); Poet, 1868, 



Repertorio, 2, p. 446. 

 Carcharias ligris Atvvood, 1S69, Proc Boston soc. nat. hist., 12, p. 268. 

 Isurus glaucus Jordan & Gilbert, 1883, Bull. 16, U. S. nat. mus., p. 28. 

 Isttrus dekayi Jordan it Gilbert, ibid., p. 874; Jord. & Everm., 1896, Bull. 47, U. S. nat. mus., p. 48; 



1900, ibid., Atlas, pi. 6, f. 21. 



