Skull of Gonorhynchna Greyl. 367 



support the epibrancliial organ. The fourth and fifth cerato- 

 branchials are slender curved rods of bone. A fifth epi- 

 branchial (text-fig., eh 5) is present in the form of a carved 

 rod of cartilage distinct from, but in the same line with, the 

 posterior cartilaginous epiphysis of the fifth ceratobranchial. 

 At its upper end it meets the Y-shaped cartilage that 

 constitutes the posterior part of the fourth epibranchial. 

 The ossified part of the fourth epibranchial consists of a 

 broad thin lamina of bone, vertically disposed, and therefore 

 seen edgewise in the text-figure. 



The first hypobranchial is as long as the first cerato- 

 branchial, the second is nearly as long as the second cerate- 

 branchial, the third hypobranchial is cartilaginous. The 

 first pharyngobranchial is wanting and there is uo spicular 

 bone ; the second and third pharyngobranchials have the 

 normal relations. 



In utilizing the characters of the skull of Gonorhynchus as 

 the basis for a discussion of the affinities of the genus I 

 think it may be taken for granted that the family Gono- 

 rbyiichidse falls within the suborder Malacopterygii as defined 

 by Boulenger (Ann. & Mag. Nat. Hist. (7) xiii. 1904-, 

 pp. 163-165), for the presence in the Gouorhynchidse of a 

 mesocoracoid element in the shoulder-girdle excludes the 

 family from the Haplomi, and the absence of Weberian 

 ossicles disposes of the hypothesis upheld by the earlier 

 writers that the Gonorhynchidae arc allied to the Cyprinoids. 

 The extension in Gonorhynchus of the upstanding process 

 of the parasphenoid so far as to touch the alispheaoid and 

 postfrontal bones is paralleled in Osteoglossum, the process 

 reaching the alispheuoid in O. Leichai'dti and the postfrontal 

 in 0. bicirrhosum and O. formosum ; and the entopterygoid 

 of Gonorhynchus bears at its posterior end a patch of stout 

 teeth, which engage with the basibranchial teeth much as in 

 Osteoylossuin ; and, further, the first basibranchial remains 

 unossified, as in Heterotis. But the Osteoglossidie [Osteo- 

 glossum, Heterotis, and Arapaima) are a sharply delimited 

 family, distinguished by the sculpturing of the superficial 

 bones of the skull, the meeting of the parietal bones, the 

 sutural union of the nasal bones with one another and with 

 the anterior ends of the frontal bones, the presence of a 

 stout peg-like process of the parasphenoid for articulation 

 with the entopterygoid, the smallness of the subopercular, 

 the bounding of the upper border of the gape by the 



