114 THE VOYAGE OF H.M.S. CHALLENGER. 



aperture on each side of the rostral projection ; a longitudinal ridge runs along the 

 infraorbital ring. Each mandibulary canal opens in front immediately behind the 

 symphysis by a slit in the skin. 



Teeth in villiform bands in the jaws, on the vomer and palatine bones, the vomerine 

 band being A-shaped and much narrower than the palatine band. 



The dorsal fin begins above the posterior third of the pectoral, and is composed of 

 densely set, fine and rather short rays, which, however, are a little longer than those of 

 the anal fin.^ Pectoral with a narrow base and feeble rays, not quite half as long as the 

 head. The ventral filaments are still shorter, very feeble, close together, and inserted 

 opposite to the rounded angle of the prseoperculum. 



The scales are cycloid, not deciduous, and rather irregularly arranged. Traces of a 

 lateral line can be distinguished at various parts of the body, but they are not continuous. 

 About thirty scales can be counted in a transverse series running from the vent to the 

 dorsal fin. The upper and lateral parts of the head, and also the rami of the mandible, 

 are covered with small thin scales. 



The gill-laminse are short, shorter than the stifi" and widely-set gill-rakers, which are 

 eight or nine in number. Of pseudobranchise only two or three small lobes can be 

 distinguished. Pyloric appendages none. 



Uniform black. 



Habitat.- — Only one specimen, in an excellent state of preservation, \\\ inches long, 

 was obtained North of Celebes (Station 198), at a depth of 2150 fathoms. 



Nematonus, n. gen. 



Bathyonus sp., Goode and Bean. 



This genus differs from Porogadus merely by the absence of spines on the head.' 



Nematonus pectoralis. 



Bathyonus pecioralis, Goode and Bean, Proc. U.S. Nat. Mus., vol. viii., 1886, p. 604. 



B. 8. D. 93. A. 73. P. 17. V. 2. 



Tail moderately elongate. Eye rather small, one-seventh of the length of the head, 

 and slightly less than that of the snout. Distance of the root of the ventrals from the 

 vent rather more than the length of the head. The penultimate ray of the pectoral pro- 

 longed, nearly twice as long as the head. About twenty-three scales in a transverse series 

 running from the vent to the dorsal fin. Eighteen long gill-rakers on the first arch. 

 Brownish-yellow, head and abdomen blackish. 



' In consequence of some injury during life, a small portion of the anal fin is lost. 



2 The operculum prohably is armed with a small spine behind, as in the majority of the fishes of this group. 



