(33G J'ROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



Color, uniform dark gray -brown, blackish below, in front, tins all 

 more or less broadly cdo-ed with whitish. Length 16i inches. 



Type No. 7185, Ichthyological Collections, Leland Stanford Junior 

 University Museum. Locality, Misaki. 



This species is known to us from 2 examples obtained at Misaki.il 

 It differs from ('<'ntr(),^rijUlum fahrlcii, t\\Qon\\ oihev species of thel 

 oenus, in having the caudal peduncle much longer and more slender,' 

 and in the shorter pectorals, which do not reach to below the first': 

 dorsal. j 



(It is named for Dr. William Emerson Ritter, of the University of.! 

 California, in recognition of his excellent work on the Tunicates andi 

 Enteropneustaiis of the Pacilic Ocean.) 



Family XIV. DALATIID^. 



SCYMNOID SHARKS. 



Sharks with no anal tin and with two dorsal tins, each without spine; 

 gill-openings small, entirely in advance of pectorals; mouth l)ut little 

 arched; a long, deep, straight, oblique groove on each side; spiracles 

 present. Oviparous, the eggs without horny case (at least in Sotnnw- 

 ms). Vertel)rie cyclospondylous. The absence of dorsal spine chiefly 

 distinguishes this family from the Squalidx^ of which these are some^i 

 what degenerate allies. Sharks mostly of the North Atlantic, some ol 

 them I'eaching a large size. 



a. Dalatiin.e: First dorsal well l^ehind ventrals; upper teeth small, pointed, lowei 



much larger, triangular Dalatias, 29. 



na. Somxiosin.e: First dorsal much in advance of ventrals. 



h. Ui)per teeth narrow; lower quadrate with a horizontal edge ending in a 

 point directed outward; body very robust, fins very small, dorsals aboul 

 equal; skin moderately rough Somniosus, 30. 



29. DALATIAS Rafinesque. 



Dalatias Rafinesque, Caratteri di Alcuni Generi, 1810, p. 13 {»parophagxis, 



description very incorrect) . 

 Scymnm Cuvier, Regne Animal, 1st ed., 1817, p. 130 {lichia; preoccupied in 



insects). 

 Scymnorhinuii Bonapakte, Cat. Pesci. Europ., 1836, p. 16 {lichia). 



Mouth transverse, a deep straight groove at each angle. Teeth in 

 jaws close set, the upper small, pointed; the lower much larger, dilated, 

 erect, triangular, not very numerous. Skin uniformly covered with 

 minute scales. Two short dorsal tins, without spine, the tirst at a 

 considerable distance from the ventrals; no anal fin. No membrana 

 nictitans. Si)iracles wide. Gill-openings narrow. . (Gunther.) 



(cJaAocr, torch, the name unexplained.) 



