272 GTMNODONTES. 



Rhyiicliotus, Batracliops, Apsiceplialus, Brachycephalus, Mouotreta, 



HoUard, Ann. Sc. Nat. 18-j7, viii. p. 275 et scqq. 

 Tetraodon, Ci-a^Taciou (Klein), Leiodon (Swains.), Cantliogaster 



(Swain.^.), Bleeher, Atl. Ichth. Gymnod. p. 49, 

 Osteolofry : see Hullard, I. c. ; Owen, Osteolog. Catcd. i. p. 81. 



Jaws divided by a median suture. Body with or without small 

 dermal ossifications. Dorsal and aual fins short, with the rays in 

 small number. 



Tropical and subtropical seas ; some species in rivers. 



Sijnopsis of the Suhgcnera and Species. 



I. The dermal ossifications are in the form of spines and of scutes, the 

 latter forming a continuous carapace round the trunk : Ilcmico- 

 niatus, m., p. 

 II. No scutes forming a carapace. 



1. Nasal organs very conspicuous. Back broad, not compressed. 



A. Nasal openings two on each side, opposite to each other, 



and situated in a single more or less prominent papilla : 

 Tetraodon, Bleek. 



a. A more or less distinct fold along the lower part of the 



tail : Gastrophysus, MiilL, p. ;?7-'). 



b. No fold along the lower part of the side of the tail or 



bodv. Body more or le?s spiny: CJieilicJithi/.^, l^Liill., 

 p. 282. 



c. No fold along the lower parts. Skin entirely smooth : 



Liosaccus, m., p. 287. 



B. Nasal opening one on each side ; it is in a simple tube, which 



is sometimes two-lipped at the extremity. Body spiny : 

 Crnyracioa, sp., Bleek., p. 288. 



C. A simple, non-perforate nasal cavity with a fringed edge. 



Body spiny: Clielonodon, Midi., p. 288. 



D. A simple circular nasal ca-sitv. Bodv smooth : Munotrettts, 



Bibr.,p. 290. 



E. On each side two solid nasal tentacles without opening : 



Arothron, MUll., p. 290. 



2. Nasal organs quite inconspicuous. Back compressed into a keel : 



Anosmius, Ptrs., p. oOO. 



I. llic dermal ossifications arc in the form of spines and of snffcs, the latter 

 forminy a co/dinuovs carapiaec round the trunh: Hemiconiatus, m. 



1. Tetrodon guttifer. 



Bennett, Proc. Comm. Zool. Soc. 18:30, p. 148. 

 Head entirely naked ; the greater part of the trunk, down to the 

 sides of the belly, covered with granulated scutes, irregular in shape 

 and size, forming a carapace as in Ostradon. The scutes pass pos- 

 teriorly into lanceolate ossifications, which are entirely hidden in 

 the skin. Throat and anterior part of abdomen with numerous 

 small two-rooted spines. Snout obtuse, the small eye being midway 



