Classijimtion of the Stomiatoid Fishes, G13 



in the vertebral centra. The caudal fin skeleton is nearly 

 as in the Clupeidiie^ without upturned vcrtebrai. 



A study of the osteology shows that the Stomiatoids form 

 two well-marked groups_, of which the Gonostomatidte and 

 Astronesthid?e respectively are the most primitive families. 

 The Gonostomatidfx? are very near the Elopidse. Comparing 

 Photichthys with Elops"^ I find a striking agreement in the 

 liead-skeleton, the general form of the skull and the relations 

 of the bones being almost exactly the same. In Photichthys 

 the orbitosphenoid appears to be absent and the posterior 

 temporal foss?e are somewhat smaller than in Elojjs, but 

 there are no other differences of importance. 



The skull of Astronesthes is much more specialized. There 

 are no distinct subtemporal or posterior temporal fosscC, the 

 f rontals extend to the posterior end of the cranial roof, and 

 the parietals are very stnall and separate. The prjemaxillaries 

 have anterior expansions which extend upwards over the 

 mesethmoid, and the maxillary has no supramaxiliaries 

 (supplemental bones). The skeleton oi Astronesthes shows 

 many resemblances to that of the Cretaceous Enchodontidae, 

 a family that may belong to this group. 



Synopsis of the Families. 



I. Prsemaxillary without anterior expansion ; maxillary with two 



supramaxiliaries, Parietals meeting above supraoccipital. No 

 barbel. Dorsal in advance or above anterior part of anal. 



Body elongate. Skull elongate, with parasphenoid 

 nearly straight, Epiotics separate ; basi- 

 splienoid and alisphenoids present. Post- 

 temporal forked : a mesocoracoid 1. Gonosto7natid(B, 



Body deep, strongly compressed. Skull short and 

 deep, with parasphenoid bent at a right-angle. 

 Epiotics meeting below supraoccipital ; basi- 

 sphenoid and alisphenoids absent. Post- 

 temporal united with supracleithrum to form 

 a rectangular bone, with short horizontal upper 

 and long vertical lower limb ; no mesocoracoid. 

 Supraneurals projecting as a keel in front of 

 dorsal tin 2. SternoptyckiidcB. 



II. Praemuxillary with strong anterior expansion extending upwards 



over ethmoid ; maxillary slender, without supramaxiliaries. 

 Parietals very small and separate, or absent. 

 A. Supracleithrum and mesocoracoid present ; dorsal in advance 

 of anal ; an adipose fin ; pectorals well developed. 



* The head-skeleton of the Elopidoe has been well described and 

 illustrated by Kidewood (P. Z. S, 1904j. 



