482 WILLIAM K. GREGORY 



premaxillaries, which are united by suture with the maxillaries, 

 and immovably connected with the cranium. 



(5) Suborder Lyomeri {Gill and Ryder) . According to Boulen- 

 ger the very anomalous abyssal forms known as Saccopharyn- 

 gidse (Gulpers), formerly set apart as a distinct order Lyomeri, 

 may be regarded as extremely degraded Eels, possibly related to 

 the Synaphobranchidse, which have entirely lost the pterygo- 

 palatine arch, the branchiostegal rays, and the pharyngeal 

 bones, the enormous slender jaws being loosely slung from the 

 cranium by means of the slender hyomandibular and quadrate. 



Superorder Uncertain (cont'd). 

 Order Symbranchii 1 Gill. 



These extraordinarily eel-like and apodal forms 2 are distin- 

 guished from the true Apodes by the following fundamental char- 

 acters: (1) The more normal structure of the skull, in which 

 the symplectic and metapterygoid are present, and the pre- 

 maxillary is well developed, forming the greater part of the oral 

 border. (2) In the more generalized family (Symbranchidas) 

 the shoulder girdle is attached to the skull through the well- 

 developed forked posttemporal, but in the Amphipnoidse the 

 absence of the posttemporal leaves the shoulder girdle free from 

 the skull, as in Apodes. (3) • The gill openings on both sides 

 are confluent into a single slit beneath the throat. (4) All 

 known members of the group parallel Lepidosiren and Protop- 

 terus among the Dipnoi, both in environment and in habits. 

 The Amphipnoidae possess lung-like respiratory diverticula of 

 the branchial chamber, on each side of the neck, which are 

 capable of taking oxygen directly from the air. From the 

 structure of the skull we may infer that the Symbranchii are 

 allied to the Isospondyli or possibly to the Haplomi. 



Superorder Uncertain (cont'd). 

 Order Heteromi 3 (Gill) . 



% (tvv, together, Ppdyyta, gills, in allusion to confluence of the gill 

 openings into a single ventral slit. 



2 Compare AppendixJL 



3 ere/009, one of two, S/x,os, shoulder, possibly in allusion to the attach- 

 ment of the shoulder to either the supraoccipital or the epiotic. 



