DISCUSSION OF SPECIES AND THEIR DISTlilBUTION. 333 



P'YCNOCRASPEDUM, Alcock. 

 PycnocraKjiedim, Alcock, Ann. and JIa<;. Nat. Hist., Nov., 1880, 386. 



Head large, body compressed, Ix.tli eovered entirely with small, tliin, smooth, rather 

 deciduous scales. Ileadboiies and opercles spineless. Snout short, broad, and not over 

 hanging the jaws, which are etpial in front. Eye of moderate size. Mout h very large; teeth 

 in villiform bands in the jaws, palatines, and vomer. No barbel, (i ill-openings wide, gill- 

 membranes entirely separate; 4 gills; S branchio.stegals; no p.sendobrancliia-. Lateral line 

 incomplete on the tail. Vertical tins invested with thick, scaly skin. Caudal free, united wit ii 

 the vertical tins at its extreme base only. Pectoral tins entire. Yeutral fins in the form of 

 bifid filaments. 



The type and only species is P. squainipiiinc, Alcock (loc. oil.), taken iu 193 fathoms in the 

 Bay of Bengal, in lat. 20^ 17' :W N., Ion. 88° DO' E. 



NEMATONUS, Gi-'inther. 



Xemalonm, GiJNTHER, Challenger Report, xxii, 1887, 111 (type, liathiioniif! pMoralis, Goode and liean). 



Body compressed, with long, tai)ering tail. Bones of head soft, muciferous channels 

 moderately developed, and with integument very thin or absent on the upjicr jiortion and 

 snout. Operculum cartilaginous and fiat; a broad process near its upper angle correspond 

 Ing to the opercular spine in some of the related genera; the head otherwise unarmed, 

 though irregular by reason of the bareness of the cranial bones. Snout much depressed, 

 broad, rounded. Jaws equal in front; mouth very wide; bands of villiform teeth in jaws, 

 ou vomer and palatines. Barbel none. Eyes small. Vertical fins coutluent; ventrals a 

 pair of bifid filaments close together, on the isthmus, close to the humeral symphysiis. Gills 

 four, with very short lamina' and rather short, imairved, acicular gill-rakers on the first 

 arch, and much shorter, less numerous, s[)atulate ones upon the three other arches. Pseu 

 dobrauchiie, rudimentary. No traces of a lateral line, though the bodyis covered with scales 

 of considerable size, almost as large as the eye, and the cheek with others still larger. 



Ncmatonu.s differs from Pon)<jatli(.s not only in the absence of sj^ines upon tlie head, as 

 Giinther has indicated, but in the much less ossified oi)ercular apparatus, iu the shorter and 

 thicker head, in the ab.sence of the three series of pores sinuilatiug lateral lines, and iu the 

 tendency to prolongation iu the lower rays of the pectoral, which increase from the up]>er- 

 most to the lowermost in Ncmatonm, while Foroyadus has a lanceolate fin, and al.-<o iu the 

 extreme exsertion of its caudal rays. 



NEMATONUS PECTORALIS, (Goode and Bean), Guntuer. (Figure li'JS.) 



Bathtjonm pectoralis, GooDE and Bean, Proc. U. S. Nat. Mns., 1885, viu, COl. 

 Nematonus pectoralis, Guntueu, Challenger Report, xxii, 1887, 114. 



Body moderately elongate, much compressed, the tail much shorter and more robust 

 than iu Bassozetus catena. Its height (20 millimeters) equals IJ times the length of the 

 head and one-seventh that of the body. 



Head stoutish, not much compres.sed, lower than body, its length (.'51 millimeters) con- 

 tained 5i times in the body length. Suout compressed, broad at its tip, its leugtii ((> milli- 

 meters) exceeding the diameter of the circular eye (.5 nullimeters). Interorbital area 

 slightly convex, its width (11 millimeters) slightly exceeding twice the diameter of the eye, 

 3 times in length of head. 



Maxilla extending far behind the eye, its length (1!) milliuu^ters) less than that of prc- 

 orbital portion of head. Mandible as long as postorbital portion of head (22 millimeters). 

 Jaws, vomer, aud palatines, with narrow bauds of villiform teeth, normally arranged. 

 Branchiostegals 8. Gill-lamelhe very short. GUI rakers long and numerous, 18 on first 

 arch below the angle, 5 above, 1 of which are rudimentary. I'seudobranchiie present, but 

 very rudimentary. 



Anterior nostrils on the top of the snout and near the median line of the lu'ad, near 

 its tip, separated by a space about equal to the diameter of the eye. Posterior nostrils iu 

 front of the eye. 



