378 Mr. C. T. Regan on the Osieohgy and 



pelvics usually absent. Piffimaxillaries not developed as 

 distinct elements ; maxillaries bordering the mouth, sepa- 

 rated anteriorly by the ethmoid*; hyo-palatine bones 

 reduced to 2 or 3, hyomandibular, quadrate, and palato- 

 pterygoid, the last sometimes absent ; lower jaw of dentary 

 and articulare ; opercular bones small, the membrane covering 

 the large branchial chambers chiefly supported by the long 

 branchiostegals. A single pair of deutigerons upper pha- 

 ryngeals, opposed to the separate lower pharyngeals. Skull 

 long and low ; prsemaxillaries, mesethmoid, and lateral 

 ethmoids represented by a single dentigerous f bone ; parietals 

 meeting in front of the supraoccipital ; no exoccipital con- 

 dyles | ; no opisthotic, but other otic bones well developed; 

 pterotic extending forward above sphenotic to alisphenoid ; 

 paired § 01 bitospheiioids; no basisphenoid. No post-temporal ; 

 supra-cleithrum attached by ligament to the vertebral column ; 

 hypercoiacoid and hypocoracoid small, laminar; no meso- 

 coracoid. Vertebrse numerous ; arches ankylosed to centra ; 

 praecaudals with strong parapophyses bearing the ribs; epi- 

 neurals and epipleurals usually present. Gonoducts reduced 

 to genital pores. 



Tlie peculiarities of the skull, jaws, suspensorium, and 

 pectoral arch se]iarate the Apodes very sharply from the 

 Isospondyli, of which they must be regarded as an offshoot. 

 They correspond to the family Mura-nidaj of Gixnther after 

 removal of the Saccopharyngidge, now generally regarded as 

 comprising a separate order, Lyomeri (see ' Annals,' Sept. 

 1912, p. 347). 



Except for the elevation of the subfamilies to family rank 

 and the addition of the more recently discovered Urenchelida% 



* According to Boulenger (Camb. Kat. Hist. p. 600) the maxillaries 

 of the Murajnidse are palato-pterygoids. I find that in all their relations 

 these bones are the same in the Muraenidse as in the other families ; 

 distally they are external to the mandibles ; moreover the true palato- 

 pterygoids are present in the usual place, but reduced to mere threads of 

 bone. 



t In Heterenchelys and also in ^ynaphohranchus the vomerine teeth are 

 separated by an interspace from the prjemaxillary teeth and the vomer is 

 a distinct bone. It can hardly be doubted that the dentigerous bone in 

 front of the vomer and between the maxillaries represents the pne- 

 niaxillaries ankylosed to the mesethmoid. 



t As in the Isospondyli an anterior half-centrum is very firmly united 

 to the basi- and exoccipitals. 



§ The orbitosphenoids lie in front of the alisphenoids and usually 

 separate the parasphenoid from the froutals ; rarely {Murimjua and some- 

 times in Anf)uill(i) ihe parasphenoid and frontals meet, concealing the 

 orbitosphenoids. 



