GREGORY: FISH SKULLS 175 



from the merely plausible. The whole work also contrasts favorably with the ordinary 

 taxonomic monograph, the chief object of which is to expose the differences between species. 



GONORHYNCHOIDEA 



Gonorhynchus. — The single existing species {Gonorhynchus greyi) of this isolated group 

 inhabits the seas off Japan, South Africa, Australia and New Zealand. It has an elongate 

 cylindrical body and a sturgeon-like head with a pointed snout, a small inferiorly-placed 

 mouth and a rostral barbel. The body and head are covered with small spiny scales. The 

 dorsal, ventral and anal fins are in the posterior half of the more or less pike-like body. 



To this family are referred the genera Notogoneus from the freshwater Eocene beds of 

 France and North America, and Charitosomus from the Upper Cretaceous of Westphalia 

 and Syria. According to Woodward (1901, p. ix), the "Gonorhynchidae are only slightly 

 modified Scopeloids, and are now shown to date back to the Cretaceous period, when all 

 the characteristic features of Gonorhynchus, except the extension of the scales over the head, 

 seem to have been already acquired." 



In the list of family characters of Scopelidae and Gonorhynchidae as given by Woodward 

 (1901, pp. 235, 271), the agreements far outnumber the differences, but it must be confessed 

 they are of a rather general character, such as the exclusion of the maxilla from the oral 

 margin by the premaxilla, the forward extension of the supraoccipital between the parietals, 

 the lack of a precoracoid process in the pectoral arch, the loss of the air-bladder, and the 

 like. On the other hand, the abdominal vertebrae of gonorhynchids, while well ossified, 

 are usually pierced by the notochord and have robust parapophyses ankylosed with the 

 centra (Tate Regan, 1929, p. 313) and bearing delicate ribs (Woodward, 1901, p. 271), 

 while in the Scopelidae the vertebral centra, though also well ossified, lack transverse 

 processes, the ribs being sessile (Boulenger, 1910, p. 611). To Woodward the differences 

 between the Gonorhynchidae and Scopelidae are less important from a phylogenetic view- 

 point than the resemblances, and he accordingly refers the two families to his very broad 

 order Isospondyli, following the Enchodontidae, a Cretaceous family that appears to be 

 related to the scopeloids (Iniomi). Boulenger (1910, p. 572) puts the Gonorhynchidae at 

 the end of the "suborder Malacopterygii" (= Isospondyli in part), while grouping the 

 scopeloids near the Enchodontidae with the Haplomi (p. 611). Tate Regan (1929, p. 313) 

 treats the Gonorhynchidae as the closing section of the Isospondyli, referring the Encho- 

 dontidae to another division of the same order and the scopeloids to the order Iniomi. 



From this and much similar evidence it appears that the "orders" Isospondyli, 

 Iniomi and Haplomi are more or less artificial groups between the extremes of which lie 

 many combinations of intermediate characters. 



A monographic comparative study of the skull of Gonorhynchus greyi has been made 

 by Ridewood (1905^) in continuation of his studies on other isospondyls. The skull 

 (Fig. 65) parallels that of the Albulidae in its small mouth and forwardly produced suspen- 

 sorium, but after a searching analysis of the cranial characters, Ridewood concludes (p. 370) 

 that although the ancestral elopids and albulids were upon the line of descent of the 

 gonorhynchids, the relationship is not nearer. 



From the excellent figures by Ridewood we may now attempt a new functional analysis 

 of the chief characters of this skull. The elongation of the snout has apparently involved 

 the pulling out of the frontals into a long narrow tract (Fig. 65). The length and narrow- 



