BY J. DOUGLAS OGILBY. 649 



As it is evidently more closely allied to T. jacksoniensis than 

 t(j T. arawatce I shall refer to it in future as 



Trachypterus jacksoxibnsis polystictus, subsp.nov. 



Contour of head and body : — The depth of the body is greatest 

 immediately behind the head, from whence it tapers gradually to 

 the slender rod-like caudal peduncle, which is evenly curved 

 upwards and forwards, and terminates in a blunt point. The 

 abdominal profile is inconspicuously crenated and apparently 

 somewhat sinuous, but the condition of the specimen is not suffi- 

 ciently perfect to justify me in definitely asserting this latter 

 character. The depth of the body at the base of the pectoral fin 

 is 3^ in the total length.* 



The upper profile of the head inclines obliquely backwards from 

 the tip of the snout to the origin of the nuchal crest so as to form 

 an angle of about forty-five degrees with the horizontal axis of 

 the body. 



The head. — Comparative measurements: — The length of the 

 headf is rather less than its depth and 54 in the total length; the 

 greatest width of the head is close behind the eye and is one-third 

 of the length. 



Jaws .-—The premaxillary processes are included within a deep 

 groove which extends backwards to above the middle Of the orbit, 

 their lencrth beinoj three-fourths of that of the head. The 

 maxillary is short and broad, its length 2'i in the head, its greatest 

 width a little more than half its length; it is of an exceedingly 

 delicate membranous structure, and is profusely ridged Avith well 

 developed stria3, which radiate from a point near its anterior 

 margin, most of the rays on the outer side being ramose; it does 



* All measuiements in which the ' ' total length " forms one of the factors 

 must be looked upon as approximate only since the curvature of the 

 vertebral column posteriorly prohibits absolute accuracy. 



t The border of the opercle on each side is greatly frayed so that it is 

 impossible to determine it accurately; I have tlierefore taken the measure- 

 ments from the tip of tiie snout to the middle of the scapular arch. 



