722 



TELEOSTEI 



II. GYMNODONTES. Supraclavicle oblique or nearly horizontal ; lower 

 three pterygials enlarged and immovably united to the coraco-scapular 

 cartilage ; anterior vertebrae with bifid divergent neural spines ; pelvis 

 absent. 



Beak with a median suture ; interoperculum not connected with suboper- 



culum ; caudal fin present ; body inflatable . 1. Tetrodontidae. 

 Beak without median suture ; interoperculum attached posteriorly to sub- 



operculum ; caudal fin present ; body inflatable. 2. Diodontidae. 

 Beak without median suture ; interoperculum attached posteriorly to sub- 

 operculum; caudal fin absent, the body non-inflatable, truncate posteriorly, 

 with the dorsal and anal fins confluent 3. Molidae. 



scL. / 



scl. 



A. 



pel. 



cl. 



pel. 



FIG. 436. Left side of pectoral arch of A, Triacanthus brevirostrix, and B, Tetrodon 

 mini,, cl, Clavicle ; cor, coracoid ; pel, post-clavicle ; p.r, pectoral rays ; ptr, ptery- 

 gials ; sc, scapula ; sd, supraclavicle. 



DIVISION I. SCLERODERMI. 



Supraclavicle vertical ; pectoral pterygials not enlarged, mov- 

 ably attached by ligament to the scapula and coracoid, three to 

 the former and one to the latter. All the vertebrae with the 

 neural arches forming a single spine. Basis cranii more or less 

 distinctly double ; dentary and articular completely co-ossified. 



Fam. 1. Triacanthidae. Praemaxillaries protractile, free 

 from the maxillaries ; teeth in the jaws separate, conical or 

 incisor-like ; palatine arch firmly united to the skull. Gills 4. 

 Praecaudal vertebrae with parapophyses ; epipleurals present. 

 Spinous dorsal fin with 2 to 6 spines. Ventral fins each repre- 

 sented by a strong spine, with an inner basal knob which locks 

 it when everted, rarely with the addition of 1 or 2 rudimentary 

 soft rays ; pelvis present, firmly united to the pectoral arch. 

 Scales small, sometimes spinous or bony. Vertebrae 20. 



Marine fishes from the Indian and Western Pacific Oceans. 

 Ten species, referable to three genera : Triacanthus, Triacanthodes, 



