382 



these bones one or two curved rod-like ones (ctenactinium) 

 are situated outside the priapium, at the aproctal side, and 

 attached to it posteriorly. An other bone (toxactinium) in front 

 of the priapium, may be present '). 



Distribution: Two genera with three species are known 

 from brackish water of Malacca and Singapore. 



i. Neostethus Tate Regan. 

 (C. TATE REGAN, Proc. Zool. Soc. London 1916, p. 2). 



Elongate, strongly compressed. Head rather small. Mouth 

 terminal, strongly oblique. One or two series of conical teeth 

 in the jaws. Dorsal fin with 5 or 6 rays, above the end of 

 the rather long anal, which has 13 16 rays. Pectorals placed 

 rather high. Ventrals wanting, perhaps represented by a pair 

 of papillae just behind the anus in the female. Caudal emar- 

 ginate. Anus, genital aperture and urinary opening behind 

 each other in the middle line below base of pectoral fins in 

 the female; behind them the abdomen is compressed into an 

 edge bearing a rayless fringe. In males the priapium is attached 

 for the greater part of its length to the head and anterior part 

 of body, only the posterior end being free. One or two ctenac- 

 tinia present. No toxactinium. A glandular longitudinal groove 

 along the upper part of the priapium, at its aproctal side and 

 continued behind into an efferent groove. Seminal papilla 

 opening into the glandular groove or into the efferent groove. 



Distribution: Two species known, from the Malay Penin- 

 sula and Singapore. 



Brackish water. 



i. Neostethus lankesteri Regan [Fig. 103, p. 381]. 



Neostethus lankesteri Tate Regan, Proc. Zool. Soc. London 1916, p. 2. 



D. 5 6; A. 15 16; P. 10 II; L.I. 34 36. 



Height 4.7, 5.7 in length with caudal. Head 4.1, 5 in length 

 with caudal. Eye 3. Origin of dorsal above last ray of anal. 

 Pectorals somewhat less than head without snout. In the male 



1) For particulars of these extraordinary structures see TATE REGAN, Proc. 

 Zool. Soc. London 1916, p. i. 



