1726 Bulletin 4.7, United States National Museum. 



Suborder GYMNODONTES. 



Plectognatlis without a spinous dorsal, with the body short and with 

 the belly inflatable; the scales typically spiniforin, with root-like inser- 

 tions (archetypically rhomboid), and with the jaws in an enamel-like 

 covering enveloped without distinct teeth. This group contains degraded 

 Plectognaths which have lost the scales, spinous dorsal, and distinct 

 teeth. In the extreme forms the pelvis, ribs, and caudal vertebrae are 

 also lost, the species depending on their dermal armature, leathery skin, 

 or inflatable belly for protection from enemies, while little power of 

 active movement remains. (yv/nvo$, naked; odovs, tooth.) 



a. Pelvis and ribs obsolete. 



b. Caudal region normally developed, with a caudal peduncle. 



c. Upper and lower jaw each divided by a median suture? maxillaries and 

 dentariea each curved outward behind the premaxillaries ; ethmoid 

 more or less projecting in front of frontals ; postfrontals extending out- 

 ward at least as far as frontals. 

 d. Yertebrae comparatively few, 15 to 21 in number;* dorsal and anal 



short, of 7 to 15 rays. 



e. Frontal bones articulated with the supraoccipital and postfrontals 

 confined to the sides; ethmoid short, narrow, little promi- 

 nent to view above; vertebras few; head broad; nostrils 

 various. TETRAODONTIDJE, CLXXII. 



ee. Frontal bones separated from the supraoccipital by the post- 

 frontals which meet in the middle ; ethmoid prominent above, 

 enlarged and narrowed forward; snout pointed; dorsal and 

 anal very short ; nostrils obsolete. 



CANTHIGASTERIDJE, CLXXIII. 



cc. Upper and lower jaw each undivided, the premaxillary and dentary bones 



coosified into sutureless arches ; maxillaries extended laterally behind ; 



body covered with stout, rooted spines. DIODONTID^, CLXXIV. 



bb. Caudal region of body aborted, the body truncated behind the dorsal and anal ; 



jaws each without median suture. MOLID^E, CLXXV. 



Family CLXXII. TETRAODONTID^E. 

 (THE PUFFERS.) 



Body oblong or elongate, usually little compressed, sometimes very 

 broad; head and snout broad ; belly capable of great inflation ; skin scale- 

 less, usually mo^e or less prickly, the spines or prickles usually weak and 

 movable, not rooted; in 1 genus (Ephippion) the skin is armed with bony 

 scutes forming a sort of carapace, approaching that seen in Ostracion: each 

 jaw confluent, forming a sort of beak which in each jaw is divided by a 

 median suture; maxillaries curved outward behind the premaxillaries; 

 lips full; nostrils various. Spinous dorsal and ventral fins wanting, the 

 fins composed of soft rays only; dorsal fin posterior, opposite and similar 

 to anal; caudal fin distinct, no ventral fins, the pelvic bone undeveloped; 

 no ribs; pectoral fins short and broad, the upper rays longest; caudal fin 

 and its vertebrae normally developed. Medifrontals articulated with the 



* The Chonerhinidce of the East Indies have vertebrae 29; D. 32 to 38; A, 28 to 32. 



