726 TELEOSTEI CHAP, 
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 60 species, 
referable to 5 genera: Vetrodon, Ephippion, Tropidichthys, Xeno- 
pterus, Chonerhinus. They inhabit all the tropical and warm seas, 
a few species being confined to fresh water. Remains of Z'etrodon 
have been found in Upper Eocene and later formations. They 
are remarkable for the manner in which they inflate themselves 
with air.’ 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. 
Fic. 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. 
