368 F. H. EDGEWOETH 



The Interhyal is the cartilage called ' Hyomandibula ' by 

 Huxley, Eidewood, v. Wijhe, and Sewertzoff, ' Symplecticum ' 

 by Krawetz, and the outer of the two ' Epihyalia ' of Greil. 

 The development, however, shows that no one of these names 

 is quite suitable, and the second suggestion of v. Wijhe is 

 adopted. 



The hyosuspensorial ligament was so called by Huxley and 

 succeeding authors. 



Comparison of the upper end of the hyoid bar with that of 

 the first four branchial bars suggests that the tract of cells 

 which separates into the above-mentioned structures is serially 

 homologous with the Epibranchialia, ?,nd it is accordingly 

 called Epihal. 



The above can be summarized as follows. A precartilaginous 

 ' tract, the Epihyal, extends from the upper end of the Cerato- 

 hyal upwards and inwards beneath, though not at first attached 

 to, the auditory capsule. This Epihyal separates into three 

 portions — from above downwards the oto-quadrate cartilage, 

 the Interhyal, and the hyosuspensorial ligament. The first- 

 named gains secondary attachments, its inner end to the base 

 of the chondrocranium and its outer end, subsequently, to 

 the Quadrate. The Interhyal chondrifies later than the 

 oto-quadrate cartilage. The hyosuspensorial ligament slowly 

 extends forwards to the Quadrate. 



Additional Literature. 



Huxley, T. H. (1876). — " On Ceratodus forsteri, with Observations on the 



Classification of Fishes ", ' Proc. Zool. Soc.' 

 ^ Krawetz, L. (1911). — " Entwickelung des Knorpelschadels von Ceratodus ", 



' Bulletin de la Societe imperiale des Naturalistes de Moscou ', Annee 



1910, Nouvelle serie, torn. xxiv. 

 "* Ridewood, W. G. (1894).— "On the Hyoid Arch of Ceratodus", 'Proc. 



Zool. Soc' 

 , van Wijhe, J. (1882). — " Ueber das Visceralskelet und die Nerven des 



Kopfes der Ganoiden und von Ceratodus ", ' Niederl. Arch. f. Zool.', 



vol. iii. 



