260 F. H. EDGFAVORTH. 



given off fi-oin tlie ca'loniic epitlieliuni ; it spreads upwai'ds 

 round the tesopliagus and doi'sal larynx, foriiiing the con- 

 strictor laryngis, and subsequently, in 9.7 mm. embryos, 

 spreads forward to the branchial region and becomes attached 

 to the OS pharyngeum superior (of van Wijhe, the I'baryngeal- 

 platte of Wiederslieim) forming the transversus dorsalis and 

 first obliquus dorsalis. The dilatator laryngis is formed from 

 the dorsal part of the oesophageal constrictor (Text-fig. 32), 

 The development of the retractor and protractor laryngis is 

 described on pp. 238 and 267. 



The development of the dorsal larynx of Amia is similar to 

 that of Lepidosteus. The forward extension of the 

 oesophageal constrictor begins in 8i mm. embryos (Text-fig-s. 

 30, 31, 32) ; it forms the transversus anterior and jiosterior 

 and. first obliquus dorsalis (of Allis). In Sal mo f ario the trans- 

 verse fibres become attached to the fifth cerato-branchial, the 

 fourth pharyngo- and epi-branchial and the third pharyngo- 

 branchial. 



The ventral larynx and musculature of Polypterus have 

 been described by Wiederslieim, who says that the muscles 

 consist of a dilatator and sphincter glottidis, the latter of 

 which is continuous below with a muscle-sheet surrounding 

 the lungs. As stated above, the dilatator is the trans- 

 versus ventralis IV. The sphincter glottidis is continuous 

 above with the constrictor of the CBSophagns, wh.ich is not 

 attached laterally to the trunk muscles. 



The development of the ventral larynx of C'eratodus 

 has been described by Xellicott, and the adult condition 

 by Wiederslieim. It may be added that the posterior edge 

 of transversus ventralis V underlies the lung, and that, though 

 there is no dorso-lai-yugeus (Wiederslieim), the lateral edges 

 of the constrictor of the (xjsophagus are attached to the 

 lower ends of the trunk-myotomes (Text-fig. 49). 



It was supposed by Gegenbauer, Wilder, Gcippert, and 

 Druner, that the cartilagines laryngei of Amphibia were 

 branchial bars, and that the laryngeal muscles were deriva- 

 tives of branchial muscles. Wilder stated that the dorso- 



