140 PEGASID^. 



Fam. 29. PEGASID^. 



Body entirely covered with bony plates, ancliylosed 

 on the trunk and moveable on the tail. Barbels none. 

 The margin of the upper jaw is formed by the inter- 

 maxillaries and their cutaneous prolongation, which 

 extends downwards to the extremity of the maxillaries. 

 Gill-cover formed by a large plate, homologous to the 

 operculum, prasoperculum, and suboperculum ; inter- 

 operculum a long fine bone, hidden below the gill- 

 plate. One rudimentary branchiostegal. The gill- 

 plate is united with the isthmus by a narrow mem- 

 brane ; gill-opening narrow in front of the base of the 

 pectoral fin. Gills four, lamellated. Pseudobranchise 

 and air-bladder absent. One short dorsal and anal 

 fin, opposite to each other. Venti-al fins present. 

 Ovarian sacs closed. 



Small marine fishes from the Indian Ocean and Australian seas. 



These fishes have been associated with the Lophobranchiatcs, from 

 which they differ in the structure of the gills, which are lamellated 

 as in other fishes. I have long hesitated to place them in the Phy- 

 sostomi, as there are characters in which they closely resemble 

 certain Acanthopterygians, and more especially the Cataphradi. 

 The structure of their pectoral and ventral fins is more that of an 

 Acanthoptorygian than a Physostomous fish. The dorsal fin is single 

 and soft ; but in this respect they resemble Aspidophoroides ; the 

 fibrous condition of their vertebrce they have in common with Am- 

 phisile (which also has abdominal ventral fins), and with other fishes 

 provided with an osseous dermal covering. However, as their 

 opercular apparatus is more incomplete than in any Acantho- 

 pterygian, I have preferred to leave them, for the present, in this 

 order*. 



One genus only is known. 



* The above remarks liad been written when I learned, from a communication 

 bv Prof. Steenstrup, that for some time he had recognized the Acanthopterygian 

 affinities of Pcffasvs, and that, in his opinion, their proper place in the system 

 would be among the Cataphracti, near to Aspidophorus and Aspidophoroides. It 

 must be a matter of regret that Prof. Steenstrup has been prevented by his 

 other labours from publishing liis researches on the subject, which, however, 

 have been referred to by Kner, in Sitzgsber. Ak. Wiss. Wien, xli. pp. 821-822. 



