PENTANCHUS PROFUNDICOLUS. 95 



by half the width of the mouth; first dorsal with not more than one fourth of its 

 base behind the bases of the ventrals; second dorsal origin above the middle of 

 the anal, base not reaching as far back as that of the latter. Base of the anal 

 two and three tenths times that of the second dorsal. Pectoral base long, fin 

 short. Scales minute, slender, simple, absent from the margins and behind the 

 bases of the fins. 



Uniform brown. 



This species is placed in Pristiurus with some doubt. The proportions of 

 the head are such as exist in that genus and in Apristurus. Preference is given 

 the former because of smaller fins and because the modified scales are rather more 

 likely to be lost than the unmodified. 



Type an adult female of twenty inches, taken off Bird Island, Hawaii, in 

 from 313 to 800 fathoms. ^ 



Pentanchus. 



Penlanchus Smith & Radcliffe, 1912, Proc. U. S. nat. mus., 41, p. 490. 



Form elongate, body cavity short; head long, depressed; snout pointed. 

 Teeth, spiracles, gill openings, mouth, nostrils, fins, and scales in most respects 

 similar to those of Pristiurus. Though it is in the great majority of its features 

 closely allied to Pristiurus and Apristurus, Pentanchus differs from both, as from 

 the other genera of the family, in the absence of the first dorsal fin. The genus 

 is found at great depths and appears to be one of the most specialized of the 

 Catulidae. 



Philippine Islands. 



Pentanchus profundicolus. 



Pentanchus profundicolus Smith & Radcliffe, 1912, Proc. U. S. nat. mus., 41, p. 490, fig., pi. 42. 



Head one fourth and body cavity about four ninths of the total length. 

 Snout long, narrowing forward ; pores large, many. Nostrils large, oblique, in the 

 posterior half of the distance from mouth to end of snout. Eye in mid length 

 of the head. Mouth wide, arched forward, with angles below the pupils, and 

 with deep grooves around the angles, that on the upper jaw reaching more than 

 half-way to the median line. Teeth small, numerous, alike in the two jaws, erect, 

 with a larger median cusp and a smaller lateral at each side of the median. 

 Scales small, leaf-shaped, with a median cusp and keel and a smaller lateral at 

 each side of it. Gill openings small, hindmost above the bases of the pectorals. 

 Spiracles small, near the orbits. A small dorsal, without a spine, above the hinder 

 half of the anal, its origin nearly half way from the first gill opening to the end 



