726 TELEOSTEI 



are coalescent, forming a beak ; parapophyses are not developed, 

 and epipleurals are absent. 



Fam. 1. Tetrodontidae. Beak with a median suture. Inter- 

 operculum a long rod, attached to inner face of praeoperculum, 

 sometimes connected with operculum, never with suboperculum. 

 Gills 3. First 4 or 5 praecaudal vertebrae with bifid neural 

 spine and closed neural arch. Skin naked or with movable spines, 

 rarely with bony plates; belly inflatable. Vertebrae 17 to 29. 



The " Puffers " or " Globe-Fishes " comprise about 6 species, 

 referable to 5 genera : Tetrodon, Epliippion, Tropidichthys, Xeno- 

 pterus, Chonerliinus. They inhabit all the tropical and warm seas, 

 a few species being confined to fresh water. Remains of Tetrodon 

 have been found in Upper Eocene and later formations. They 

 are remarkable for the manner in which they inflate themselves 

 with air. 1 The flesh of most species is poisonous. 



Fam. 2. Diodontidae. Beak without median suture. Inter- 

 operculum rod-like, attached posteriorly to the rod-like anterior 

 limb of the suboperculum. Gills 3. All the praecaudal vertebrae 

 with bifid neural spines. Skin with movable spines ; belly inflat- 

 able. Vertebrae 21 or 22. 



FIG. 439. Diodon geometricus. (After Goode. ) 



Only two genera appear capable of clear definition : Diodon 

 and Lyosphaera ; species about 15. Numerous species have been 

 described from the Upper Eocene and later formations. 



" Porcupine Fishes " are confined to tropical seas, and have 

 attracted attention from the earliest times, being frequently pre- 

 served as " curiosities." Their flesh is regarded as poisonous. 



Fam. 3. Molidae. Beak without median suture. Inter- 



operculum rod-like, attached posteriorly to the rod-like anterior 



limb of the suboperculum. Gills 4. . Anterior praecaudal vertebrae 



with divergent bifid neural spines and neural canal not roofed in. 



1 Cf. Thilo, Anat. Anz. xvi. 1899, p. 73. 



