DISCUSSION i >F SPECIES AND THEIB DISTRIBUTION. 333 



PYCNOCRASPEDUM, Alcock. 

 Pycnocraapedum, Ai.cock, Aim. ami Mag. Nat. Hist., Nov., L889, 386. 



Bead Large, body compressed, both covered entirely with small, thin, smooth, rather 



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

 hanging the jaws, which are equal in front. Bye of moderate size. Mouth very large; teeth 

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

 membranes entirely separate; i gills; 8 branchiostegals; no pseudobranchise. Lateral line 

 incomplete on the tail. Vertical tins invested with thick, scaly skin. < Jaudal free, united wit h 

 the vertical tins at its extreme base only. Pectoral tins entile. Ventral fins in the form of 

 bifid filaments. 



The type and only species is /'. squamipinne, Alcock (loc. tit.), taken in I'M fathoms in the 

 Bay of Bengal, in lat. 20 17 30" N., Ion. 88° 50' E. 



NEMATONUS, Gunther. 



Nematonus, Gunther, Challenger Report, xxn, 1887, 114 (type, Bathyonus pectoralis, Goode and Bean). 



Body compressed, with long, tapering tail. Bones of head soft, muciferous channels 

 moderately developed, and with integument very thin or absent on the upper portion and 

 snout. Operculum cartilaginous and Hat; 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, 

 on vomer and palatines. Barbel none. Eyes small. Vertical tins continent: ventrals a 

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

 lour, with very short laminae and rather short, incurved, acicular gill-rakers on the first 

 arch, and much shorter, less numerous, spatulate ones upon the three other arches. Pseu 

 dobranchise 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. 



Nematonm differs from Porogadm not only in the absence of spines upon the head, as 

 Gunther has indicated, but in the much less ossified opercular apparatus, in the shorter and 

 thicker head, in the absence of the three series of pores simulating lateral lines, and in the 

 tendency to prolongation in the lower rays of the pectoral, which increase from the upper 

 most to the lowermost in Nematonus, while Porogadus has a lanceolate fiu, and also in the 

 extreme exsertion of its caudal rays. 



NEMATONUS PECTORALIS, (Goode and ISeax), Gunther. (Figure 295.) 



Bathyonus pectoralis, Goode and Bean, I'roc. U. S. Nat. Mas., 1885, vin, 604. 

 Nematonus pectoralis, G&ntheb, Challenger Report, xxn, 1887, 114. 



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

 than in Ba880zetv& catena. Its height (1!G millimeters) equals 1J times the length of the 

 head and one seventh that of the body. 



Head stoutish, not much compressed, lower than body, its length (34 millimeters) con- 

 tained o : \ times in the body length. Snout compressed, broad at its tip, its length (0 milli- 

 meters) exceeding the diameter of the circular eye (.3 millimeters). 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 (19 millimeters) less than that of pre 

 orbital portion of head. Mandible as long as postorbital portion of head (-2 millimeters), 

 .laws, vomer, and palatines, with narrow bauds of villiform teeth, normally arranged. 

 Branchiostegals 8. Gill lamellae very short. Gill rakers long and numerous, 18 on first 

 arch below- the angle, 5 above, 4 of which are rudimentary. Pseudobranchise present, but 

 very rudimentary. 



Anterior nostrils on the top of the snout and near the median line of the head, near 

 its tii>, separated by a space about equal to the diameter of the eye. Posterior nostrils in 

 front of the eye. 



