232 THE PLAGIOSTOMIA. 



equal, with a deep and rather short groove and short labial folds, one fourth as 

 long as the jaw, at each angle. Teeth small, compressed, with three sharp 

 pointed cusps of which the median is largest, in about 70 rows. Eye large, length 

 of orbit equal its distance from the end of the snout. Spiracle about once its 

 diameter farther back from the edge of the orbit, at a level above the eye, open- 

 ing upward. Gill openings in front of the pectoral, width about two thirds the 

 length of the orbit. Pectorals less than twice as long as broad; margins all con- 

 vex, hinder oblique; inner angle longer than the outer but not produced. First 

 dorsal entirely in the forward half of the total length, spine behind the ends of 

 the pectorals; length of base without the spine one fifth of the distance between 

 the two spines, or equal the length of the base of the second dorsal, or half the 

 distance from the base of the latter to the supracaudal fin, upper margin broadly 

 curved and continued to the hinder angle, which latter is hardly produced. 

 Second dorsal somewhat larger than the first, depth about one and one half times 

 that of the first, hind margin httle concave, upper angle blunted, hind angle pro- 

 duced; spine above the axils of the ventrals, one half longer than that of first 

 dorsal, half or more exposed. Caudal of moderate depth, about two fifths of 

 the total length; subcaudal deep, lobe not produced, separated from the terminal 

 by a shallow notch. Scales minute, with broad radiate base from which rises a 

 slender sharp and hooked spine. 



Uniform dark brown. 



Atlantic, Greenland to New York. 



Centroscyllium ritteri. 



Centroscyllium ritteri Jordan & Fowler, 1903, Proc. U. S. nat. mus., 26, p. 635. 



Head very broad, depressed; snout short, broad, rounded in front. Eye 

 large. Nostrils large, midway from eye to end of snout. Mouth about midway 

 from end of snout to first gill opening, a labial fold at the corners. Teeth tricus- 

 pid, alike in the two jaws. Spiracles large. Pectorals short, broad, angles 

 rounded, hind border subtruncate, not reaching below the first dorsal. Dorsal 

 spine immediately behind the ends of the pectorals; hind border of fin oblique. 

 Spine of second dorsal above axils of ventrals, much taller than that of the first, 

 nearly as high as the fin, more than half exposed, placed nearly halfwaj^ from the 

 gill openings to the end of the tail ; fin rather longer than that of the first dorsal ; 

 base, excluding the spine, equal about one half its distance from the supracaudal, 

 or about one fourth of the distance between the two spines. Caudal moderate, 

 nearly equal in length to the distance from one dorsal spine to the other. 



