1902.] PLECTOGXATHOUS FISHES. 303 



small specimens of this species with Bleeker's tyjDe specimen has 

 convinced me of their specific identity. The supposed diffei^ence 

 in the nasal organs is non-existent, they might impartially be 

 described either as a short tube with two terminal lij)s, or as two 

 tentacles united basally, although the former phrase is more 

 applicable to the smaller specimens, the latter to the larger, as 

 might be expected from what we know of the evolution of these 

 organs. 



Tetrodon pustulatus Murray. 



The nasal organs in this species are almost exactly similar to 

 those of the closely allied Tetrodon patoca, which has been placed 

 in a difierent section on account of supposed differences in these 

 organs. 



Tetrodon borneensis, n. sp. (Plate XXIY. fig. 3.) 



Nasal organ an elevated tube, very indistinctly two-lipped, 

 with a single terminal aperture. Body rather compressed, with 

 dorsal keel more or less distinct, the caudal peduncle twice as 

 deep as broad and not longer than deep. Length of head about 

 2 1 times in the total length ; snout not longer than broad, half 

 the length of head ; nasal organs midway between eye and end 

 of snout ; eye-diameter 3|-4| times in the length of head, inter- 

 orbital width about 21- times ; ethmoid very narrow. Jaws sub- 

 equal in height, the upper somewhat projecting, with fairly 

 well-marked ridges on each side of the median groove ; cutting- 

 edges concave. Spines small, numerous, extending on the head 

 and body from the level of the nostrils to that of the vent. D. 11. 

 A. 10, rounded, not elevated. Caudal rounded. 



Dark brown above, lighter below. A light cross-band between 

 the eyes is continued forward on each side from the eye through 

 the nasal organ to the end of the snout, and a broader band runs 

 back on each side from the eye to meet its fellow in the mid- 

 dorsal line. Sometimes irregular bands or reticulations on the 

 sides and caudal fin. Dorsal and anal immaculate. 



Sarawak. Total lens:th 70 mm. 



EXPLANATION OF THE PLATES. 



Plate XXIV. 



Fig. 1. Pfsetidomonacanthus clegeni (natural size), p. 299. 



2. Tetrodon pleurocfram-ma (natural size), p. 300. 



3. „ boj'neensis (natural size), p. 303. 



Plate XXV. 



Fig. 1. Fseudomonacanthus multimaculatus (reduced to /j ), p. 298. 

 2. „ pniictulatus (reduced to ^'j), p. 298. 



