404 



TELEOSTEI 



(Muraenidae), or disappear (Synaphobrauchidae, Saccopharyngidae). 

 In fact, the interpretation of the bones of the upper jaw is often 

 doubtful. The symplectic is absent, and the mandible contains 

 only an articular and a deritary. 



The pectoral girdle has become freed from the skull, there 

 being no post-temporal (Fig. 399). Often more than five radials 

 are found in the pectoral fin, a peculiarity which is to be noticed 

 in Gymnotus and the Muraenolepidae. 



'f. 



r. 



Fia. 399. 



Skeleton of the left half of the pectoral girdle and of the tin of Anguillu vulgnris, L. 

 c, coracoid ; cl, cleithrum ; /, foramen ; r, eighth radial ; s, scapula ; scl, supraclavicle. The- 

 cartilage is dotted. 



The scales are rudimentary or absent. -The branchial opening 

 becomes much narrowed ; the air-bladder has an open duct and 

 there are no pyloric caeca. The ova are discharged through mere 

 genital pores (p. 367). 



The remarkable deep-sea form, long known as Leptocephalus, has 

 been shown to be the larval stage of the Anguilliformes, which 

 metamorphoses into the elver ; the latter grows into the adult 

 form (Delage [Ilia], Grassi [182o]). 



Division 1. ARCHENCHELI. 



The caudal fin and hypural bones are still present, also the- 

 pelvic fins. The jaws are toothed, and the palatopterygoid arch 

 is normally developed. The scales are vestigial or absent. 



Family URENCHELIDAE. Represented by extinct genera from Cre- 

 taceous strata. 



Urenchelys, A. S. W. ; Cretaceous, England and Mt. Lebanon. 

 Anguillavus, Hay ; Cretaceous, Mt. Lebanon. 



