Classification of the Order Synentognathi. 331 



projection fitting an emargination of an anterior laminar 

 expansion of the neural arch behind it ; in the posterior 

 caudal region the hsenial arches articulate in a somewhat 

 similar manner, but on the anterior caudal and posterior 

 praecaudal vertebrae the posterior processes are longer and 

 directed vertically downward. 



I find that the structure of the jaws, the pharyngeal bones 

 and teeth, the skull, the pectoral arch, and the pelvic bones 

 call for the recognition of two very distinct suborders, each 

 including two closely related families. 



Order SYNENTOGNATHI. 



Suborder 1. Scombresocoidea. 



Synentognaths with small scales and with the mouth 

 typically large, the jaws usually produced and narrowed 

 forwards; rami of the lower jaw united by the interlocking 

 of a series of inner processes (except in Culolabis) ; maxillaries 

 firmly united to prsemaxillaries. Third upper pharyngeals 

 moderately enlarged, separate ; fourth usually present ; lower 

 pharyngeal triangular or long and narrow. Pharyngeal teeth 

 usually villiform or granular, some of the teeth of the 

 principal plates often compressed, tricuspid. Parasphenoid 

 without apophysis ; myodorae elongate, the parasphenoid 

 and pro-otic meeting in a long sutural union ; auditory 

 bulla, if distinct, little prominent, with but a shallow depres- 

 sion in front of it. Post-temporal more or less expanded 

 and laminar, simple or with a small inner fork ; supra- 

 cleithrum small, partly or entirely hidden by the post- 

 temporal; cleithrum connected with basioccipital by a strong 

 ligament. Each pelvic bone of an anterior subtrianguiar 

 lamina and an erect laminar process, which is more or less 

 expanded superiorly. 



Family 1. Belonidae. 



Post-temporal forked, the upper fork more or less ex- 

 panded, anteriorly attached to the nearly horizontal epiotic 

 and pterotic lamina, the lower fork short and slender, 

 attached to a process of the exoccipital lamina ; supra- 

 cleithrum small, vertical, more or less concealed beneath the 

 post-temporal. Vertebrse 57 to 77 {o7 in Xenentoclon *, 7-1 

 in Potamorrhaphis, 77 in Belone) ; prsecaudals with strong 



* 57 also in the Miocene Belone tenuis (Ki-amberger, Glasnik Soc. Hist. 

 Nat. Croatia, x. 1898, p. 26, pi. ii. fig. \). 



22* 



