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body is contained, when the pubic bona is extended, two and two- 

 third times in the total length ; the two front teeth are triangular 

 and by their union form a pointed edge ; the others are also 

 pointed ; the body is entirely covered with a very fine velvety 

 granulation. 



The colour is entirely of a light and rather brilliant green, 

 darker on the back, rather yellow on the belly ; the eyes and 

 teeth are also green ; the caudal of the same colour ; second 

 dorsal and anal transparent, rather dark on the edge. 



Only seen once in the month of March ; it is rather over two 

 and a-half inches long, and has an oval form. 



JSTota. None of the three sorts of Monacanthus, I here describe, 

 have any particular spines or spots on the sides of the tail. 



GYMNODONTES. 



" Body more or less shortened. The bones of 

 the upper and lower jaw are confluent, forming a 

 beak with a trenchant edge, without teeth, with or 

 without medium suture. A soft dorsal, caudal, 

 and anal are developed, — approximate. No spinous 

 dorsal. Pectoral fins, no ventrals. 



" Marine fishes of the temperate and tropical 

 regions. Some species confined to fresh water." 



Group TETBOBONTINA. 



Tail and caudal fin distinct. Part of the oesophagus much exten- 

 sible, and capable of being filled with air ; no pelvic bone ; air- 

 bladder present. 



TETRODON. 



Found in all the warm or tropical seas of the world. They are, 

 generally poisonous. I have observed two sorts on the shores of 

 Hobson's Bay. 



