EEPOUT ON THE DEEP-SEA FISHES. 229 



Platytroctes. 



Platytrodes, Giinth., Ann. and Mag. Nat. Hist, 1878, vol. u. p. 249. 



Body rather abbreviated, much compressed, and covered with small keeled scales. 

 Mouth of moderate width; the mazillary, intermaxillary, and mandible armed with a 

 single series of small teeth. Palate nearly smooth. Eye rather large. The dorsal and 

 anal fins opposite to each other, on the tail, moderately long. Adipose fin absent. 

 Caudal forked. Pectoral small. Ventrals none. Each clavicle terminates below in a 

 long, projecting, acute spine, the two spines coalescent. Gill-opening wide; six branchio- 

 stegals. Gills very narrow, pseudobranchise present ; gill-rakers long, lanceolate. Pyloric 

 appendages rudimentary. 



Platytt^ctes opus (PI. LVIII. fig. A). 



Platytroctes apics, Giinth., Ann. and Mag. Nat. Hist., 1878, vol. ii. p. 249. 

 D. 18. A. 17. P. 20. L. lat. ca. 100. 



The height of the body is more than one-third of the total length (without caudal) ; 

 the diameter of the eye one-third of the length of the head. The maxillary does not 

 extend to below the middle of the eye. 



Habitat. — Mid- Atlantic, Station 107; depth, 1500 fathoms. One specimen, 5^ inches 

 long. 



The body of this fish is much compressed and deep, but, singularly, the convex 

 portions on the dorsal and ventral halves are merely a fold of the skin, into which neither 

 the muscles nor the abdominal organs enter. The greatest depth of the body is at about 

 the middle of its length, and contained in it twice and three-fourths, not including the 

 caudal. The head is likewise compressed, of moderate dimensions, two-sevenths of the 

 length of the body. Head longitudinally concave above, the concavitj^ being bordered 

 on each side by a perforated muciferous canal, and broadest behind, but tapering to a 

 point between the nostrUs. The bones of the head are rather tliin, but less so than in 

 Bathytroctes. Eye large, one-third of the length of the head, as long as the snout, 

 and situated immediately below the upper profile. Infraorbital ring incomplete, the 

 muciferous canal not being prolonged beyond the prseorbital. Mouth rather small, wdth 

 the lower jaw projecting when the mouth is open. Maxillary broad, short, extending to 

 the front margin of the eye. Dentition very feeble ; teeth uniserial, uniformly minute, 

 occupying the whole extent of the intermaxillary and maxillary, but confined to the front 

 part of the mandible ; only a few rudimentary teeth are visible on the side of the 

 mandible. Vomer with a minute tooth on each side ; palatines toothless. 



Brauchiostegals extremely slender, curved. Gills four, the inner one very short ; 



