276 DR> W. G, RIDEWOOD ON THE 



bone. Projecting downward from each second hypobrancbial is 

 a stout process, similar to that which occurs in the same position 

 in Osteoglossum and Seterotis. The epipharyngeal teeth of each 

 side are disposed in two contiguous patches. 



The foregoing description of the skull of Pantodon, read in 

 relation with the summary of the features of the skull in the 

 Osteoglossidse, points unmistakably towards the existence of a 

 close alliance between the Pantodontidse and the Osteoglossidse. 

 The superficial bones of the skull of Pantodon are not sculptured, 

 it is true; and the confluence of the right and left premaxillse 

 is suggestive of the MormyridjB rather than of the Osteo- 

 glossidse ; but, taking the skull as a whole, the evidence is fairly 

 convincing. 



The nasals are large and are incorporated into the cranium, 

 and although they do not meet in a median suture as do the 

 nasal bones of the Osteoglossidse, they resemble these in being 

 suturally united with the anterior edges of the frontal bones. 

 The meeting of the parietal bones in the median line, the small- 

 ness of the mesethmoid, the failure of the eye-muscle canal to 

 open posteriorly, the absence of air-vesicles in the hinder part 

 of the cranium, the bounding of the side of the gape by the large 

 maxillary bone, and the absence of a surmaxilla, are characters 

 common to Pantodon and the Osteoglossidse ; and — strongest 

 evidence of all — the entopterygoid of Pantodon articulates with 

 a lateral peg of the parasphenoid in a manner unknown in any 

 fishes but the Osteoglossidse. In the great development of the 

 linguar dentition, in the toothing of the parasphenoid and vomer, 

 and in the fusion of the palatine with tlie ectopterygoid, Pantodon 

 bears a closer resemblance to Osteoglossum and Arapaima than 

 does Reterotis to these ; but in the absence of a subopercular, 

 and in the want of a roof to the posterior temporal groove, 

 Pantodon departs from Osteoglossum and Arapaima, and 

 approaches Seterotis. 



Peters, in the original description of Pantodon {I. c. p. 200), 

 placed the genus in a special subfamily, the Pantodontes, which 

 he intercalated between two other subfamilies, the Hyodontes 

 {Syodon) and the Osteoglossa {Heterotis, Arapaima, Osteo- 

 glossum), the three subfamilies constituting the family Osteo- 

 glossidse. Giinther ('Study of Pishes,' 1880, p. 653) raised the 

 subfamilies of Peters to family rank, malting them the Hyo- 

 dontidse, Pantodontidse, and Osteoglossidse. Boulenger, in his 



