Classification of the Ordar Synentognathi. 333 



Family 2. ScombresocidaB. 



Post-temporal simple, a broad lamina anteriorly overlapping 

 the nearly vertical epiotic and pterotic lamina ; supra- 

 cleithrum a small bone adherent to the inner face of the 

 post-temporal at its posterior edge. Vertebrae 65-/0 *, 

 parapophyses mostly very short, with the ribs nearly sessile. 

 Jaws more or less produced and attenuated forwards ; teeth 

 very small. Posterior rays of dorsal and anal detached 

 tinlets. 



Two genera, Scombresox, Lacep., and Cololabis, Gill. In. 

 both the pharyngeal bones and teeth are much as in Belone ; 

 the third upper pharyngeals are moderately large, separate, 

 and are followed by the very small fourth pair, which bear 

 a few teeth ; the lower pharyngeals form a moderately broad 

 triangular plate. In Scombresox the structure of the jaws is 

 exactly as in the Belonidse, even to the presence of the inter- 

 locking processes which unite the produced portions of the 

 rami of the lower jaw; the absence of these anterior exten- 

 sions in Cololabis may be regarded as probably secondary. 



S uborder 2. Exoccetoidea. 



Synentognaths with rather large scales and small mouth. 

 Second and third upper pharyngeals dentigerous, the third 

 pair strongly enlarged, together forming a somewhat convex 

 ovoid plate ; fourth upper pharyngeals absent ; lower 

 pharyngeal broad, triangular, with concave upper surface ; 

 teeth on principal pharyngeal plates anteriorly villiform, 

 posteriorly incisors with transversely expanded horizontal 

 edge, the two types connected by teeth of intermediate 

 form, many of which are tricuspid. Parasphenoid with an 

 inferior apophysis in front of the upper pharyngeals ; myo- 

 dome short, a deep depression between its outer wall and the 

 prominent compressed auditory bulla. Post-temporal and 

 supra-cleithrum simple^ slender, curved, the former attached 

 along the posterior edge of the pterotic lamina ; supra- 

 cleithrum suspended from the posterior end of the post- 

 temporal; cleithrum curved inwards above, articulating 

 directly with basioccipital. Each pelvic bone of an anterior 

 subtriangular lamina and an erect slender process. 



* 65 in Sco7nbresox saurus ; 70 in the Miocene Scombresox acutirostris 

 (Sauvage, Ann. Sci. G4ol. iv. 1873, no. 1, fig. 68, and xi. 1880, no. 3, 

 p. 48). 



