238 THE PLAGIOSTOMIA. 



transverse. Mouth transverse, with a straight deep groove, covering the labial 

 folds, at each angle, ending at the end of a transverse fold in front of and covering 

 a distinct upper lip. Upper teeth raptorial, slender, subcorneal; lower sectorial, 

 compressed, with a smooth-edged triangular cusp, erect. Gill openings narrow. 

 Pectorals, dorsals, and ventrals small, caudal short. Tail without lateral folds or 

 caudal pits. Scales minute, polygonal or quadrangular with a central depression 

 on the crown, in pavement. 



ISISTIUS BRASILIENSIS. 



Scymnus brasiliensis Quoy & Gaimard, 1824, Voy. Uran., Poiss., p. 198. 



Squalus (Scymnus) fulgens F. D. Bennett, 1840, Narrative whaling voyage, 2, p. 255; G. Bennett, 



1860, Gatherings nat. Australasia, p. 66. 

 Scymnus (Scymnus) brasiliensis Muller & Henle, 1841, Plagios., p. 92; Dumeril, 1865, Elasm., p. 453. 

 Scymnus (Scymnus) brasiliensis var. torquatus Muller & Henle, 1841, loc. cit. 

 Scymnus (Scymnus) brasiliensis var. unicolor Muller & Henle, 1841, loc. cit. 

 Dalatias brasiliensis Gray, 1851, Choudropterygii, p. 76. 

 Leiusferox Kner, 1865, Denk. Akad. wiss. Wien, 24, p. 10, pi. 4, f. 2. 

 Isistius brasiliensis Gill, 1865, Proc. Acad. nat. sci. Phil., p. 264; Gunth., 1870, Cat. fishes Brit, mus., 



8, p. 429; Peters, 1876, Monats. Berl. akad., p. 853; Garman, 1899, Mem. M. C. Z., 24, p. 34, 



pi. 1, f. 1, pi. 2-3, pi. 69, f. 2. 

 Leius brasiliensis Gunth., 1910, Siidsee fische, 3, p. 490. 



Body cavity about two thirds and caudal fin about one sixth of the total 

 length. Head subconic, crown somewhat flattened; nostrils in front, valve with 

 a short sharp process in the middle. Eye large, orbit with an angle in the hind 

 border. Mouth moderate, transverse, with a deep groove at each angle, with 

 labial folds, and with distinct upper lip. Teeth dissimilar, smooth-edged; upper 

 in 33 rows, slender, pointed, more or less oblique and moveable, several series 

 in function; lower broad, with erect triangular cusp, in 31 rows, a single series 

 in function, except when the outer is about to be dropped. Spiracle large, behind 

 the eye about one length of the orbit, at a higher level, opening upward. Gill 

 openings small, narrower than the spiracle, rather above the level of the pectorals. 

 Pectorals small, subtruncate, angles rounded. First dorsal very small, end of 

 base above origins of ventrals, hind margin truncate. Second dorsal little larger 

 than the first, end of base near the middle of the space between the bases of the 

 ventrals and the base of the caudal, fin triangular. Depth of caudal about equal 

 its length, subcaudal portion produced in a lobe longer than the balance of the fin 

 anterior to the shallow notch separating it from the terminal. The lateral folds 

 said to occur on the tail were caused by contraction of the tissues in preservation. 

 Total length 20, snout to vent 132, snout to dorsal 12, snout to pectorals 3|, 

 snout to mouth l| and caudal fin 3| inches. 



