272 OVMN DONTDS. 



Rliynchotus, Batracliops, Apsici jilinlus, Ih'.aohycephalus, 3Iouotreta, 



Holldrd, Ann. <S'c'. Ned. IH-jJ, viii. p. 27') rt scqq. 

 Tetraodou, Crayraciou {Klein), Jjeiodon -(Swains.), Cantliogaster 



(Swains.), Bleehcr, All. Ichth. Grjninod. p. 40, 

 Ostcolog-y : see Hullard, I. c. ; Owen, Odenlufi. Catal. i. p. Hi. 



Tmws divided by a median suture. Body witli or without small 

 dermal ossifications. Dorsal and an^l fins short, with the rays in 

 small number. 



Tropical and subtropical seas ; some species in rivers, 



SijnnpKts of the SnJn/cnera and Specie?. 



1. TIiG dovnial ossifications are in the form of spines and of scutes, the 

 latter forming a continuous carapace round the trunk: Ilemico- 

 'ni(das, m., p. 

 1 1. Xo 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 : 

 Tctraodon, Bleek. 

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

 tail : Gastroj^hi/sus, Midi., p. 273. 



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

 body. Body more or less spiny : Cheilichthjs, Miill., 

 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-hpped at the extremity. Body spiny : 

 Crui/racion, sp., Bleek., p. 288. 



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

 Body spiny: Chclonodon, ^liill., p. 288. 



1). A simple circular nasal cavity. Body smooth : Monotrefus, 

 Bibr.,p. 200. 



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

 Arothron, Midi., p. 200. 



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



Anosmius, Ptrs., p. 300. 



!. Tlir dcnml nssifcations are in the fonn of spines and of scutes, the latter 

 ft)r)nin(j a continuous carapace round the trunk : Hemiconiatus, »i. 



1. Tetrodon guttifer. 



/)( inicft, I'rocj Comm. Zool. Sue. 18.jO, p. 148. 

 l[eu<l "utirely naked; the greater pail of the trunk, down to the 

 sides (jf the l)elly, covered with granulated scutes, irregular in slmp'c 

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

 t-iiorly into lanceolate ossificatioiis, which are entirely hidden in 

 th(^ skin, liivoat and anterior part of abdomen with numerous 

 -nnll two-rooted S|.ines. Snout oblusej the small eye being midway 



