288 MR. C. TATE EEGAX ON [ISTov. 4, 



line. Dorsal with V-YI spines. Soft dorsal and anal rather 

 shorter than in Triacanthus ; ventrals usually with one or two 

 rudimentary soft rays ; caudal rounded. Jaws with a series of 

 conical teeth, and usually a few inner teeth. Hollardia Poey 

 seems not distinct from this genus. 



3. Halimochirtjrgus Alcock.— Body low, compressed, with 

 short caudal peduncle. Scales small, spinate. No lateral line. 

 Snout much produced, lower jaw projecting. D. II, 13 ; A. 12. 

 Yentrals without soft rays. Caudal rounded. Teeth very small, 

 conical, in a single series. 



Family 2. TRior)OXTiD.E. 



Prfecaudal vertebrse without parapophyses ; epipleurals well- 

 developed. Premaxillaries not protractile, firmly united to the 

 maxillaries ; teeth in the jaws coalescent. Pelvis represented by 

 a single long bone, movably attached to the pectoral arch. No 

 spinous dorsal ; soft -dorsal and anal short ; no ventrals. Abdomen 

 with a dilatable sac, kept expanded by the movable pelvis ; lower 

 part of sac a flap of skin into which the air does not enter. In 

 other characters like the Triacanthidte. 



Genus. 



Triodon. — Body compressed, caudal peduncle long and slender. 

 Scales osseous. Caudal forked, with 18 rays. Twenty vertebrae. 



Although unable to examine a skeleton of this genus, a study 

 of the figures and descriptions published has convinced me that 

 the skull, vertebral column, and pectoral arch are extremely like 

 those of Triacanthus, whilst the scales, movable pelvis, ventral 

 sac and flap are similar to those of the Balistidse. The only 

 features which link this family to the Tetrodontidse, in the 

 neighbourhood of which it has generally been placed, are the 

 comparatively unimportant characters of the coalesced teeth and 

 absent spinous dorsal. It would be interesting to know whether 

 the fourth upper pharyngeals are well-developed and toothed, as 

 in TriacantJms, oi- rudimentary and toothless, as in Balisies. 



Family 3. Balistid.e. 



Pr?ecaudal vertebras with well- developed parapophyses to which 

 epipleurals are attached. Praporbital more or less ossified. 

 Ethmoid region long, without distinct nasal cavities. Palatine 

 movably articulated with ectopterygoid, or else entirely free from 

 it. Premaxillaries not protractile, firmly united to the 

 maxillaries. Fourth upper pharyngeals rudimentary, not toothed. 

 Incisor-like teeth in the jaws. Pelvis long, movable. Spinous 

 dorsal with one to three spines, the first, if strong, followed by a 

 second which locks it when erected. Soft dorsal and anal long or 

 of moderate length. Yentrals, if present, represented by a single 



