(Günth., Fishes, iii., p. 385.) 5. _Catopra siamensis._ D. 13/15. A. 3/9. L. lat. 27. L. transv. 5-1/2/13. The height of the body is contained twice and a third in the total length, the length of the head thrice and a third; head as high as long. Snout rather shorter than the eye, the diameter of which is one-fourth of the length of the head, and equal to the width of the interorbital space. The lower jaw is scarcely longer than the upper, and the maxillary extends slightly beyond the anterior margin of the orbit. Two nostrils remote from each other, both very small. Præorbital and angle of the præoperculum slightly serrated; opercles, throat, and isthmus, entirely scaly. The dorsal fin commences above the end of the operculum, and terminates close by the caudal; its spines are very strong, and can be received in a groove; the fifth, sixth, and seventh are the longest, not quite half as long as the head; the last spine is shorter than the penultimate; the soft dorsal is elevated and scaly at the base. The second anal spine is exceedingly strong, rather stronger and longer than the third, and not quite half as long as the head; the soft anal is similar to the soft dorsal. Caudal fin rounded, slightly produced, one-fourth of the total length; its basal half is scaly. Pectoral rather narrow, as long as the head without snout. The ventral is inserted immediately behind the base of the pectoral; it has a strong spine, and extends to the vent. Scales minutely ciliated: the upper part of the lateral line terminates below the last dorsal rays, the lower commences above the third anal spine. Gill-membranes united below the throat, not attached to the isthmus, scaly. Four gills, a slit behind the fourth; pseudobranchiæ none. The jaws, vomer, palatines, and upper and lower pharyngeals are armed with bands of small villiform teeth. Very remarkable are two large, ovate, dentigerous plates, one at the roof, the other at the bottom of the mouth, in front of the pharyngeals; these plates are slightly concave in the middle, pavimentated with molar-like teeth, and have evidently the same function as the pharyngeal dentigerous plates of the true Pharyngognathi. Total length 52 lines. (Günth., Proc. Zool. Soc., 1862, June 24.) 6. _Ophiocephalus siamensis._ D. 42. A. 27. L. lat. 65. L. transv. 5/11.