SKELETOlSr AND LARYNX OP XENOPTJS AND PIPA. 55 



portion of the ventral wall of the larynx of both Xenopus and 

 Pipa is in reality the hinder part of the median hyobranchial 

 plate, and that the rod- like ossifications in the laryngeal skeleton 

 are the columellae or thyrohyal bones of other Anura. 



The account given by Hoffmann (20) is culled almost entirely 

 from Henle's treatise, many paragraphs being verbatim extracts. 

 Hoffmann, however, does not seem to have had a clear idea of the 

 nature of the coalescence of the skeletal parts described by 

 Henle ; for in two places he speaks of a fusion of the arytenoid 

 cartilage with the body of the hyoid, unjustifiably substituting 

 " cartilago-arytsenoidea " in the one place (p. 518) for " Stimm- 

 ladenknorpel " of Henle (p. 16), and in the other (p. 524) for 

 " EiDgformiger Knorpel " of the same author (p. 26). Parker 

 (33), in his exhaustive work on the skull of Batrachia, gives good 

 figures of the hyobranchial skeleton of larval and adult stages of 

 both Xenopus and Pipa. He ignores Henle's view of the mode of 

 formation of the hyoglossal foramen, and by labelling the car- 

 tilage which, bounds it in front the first basibrancbial, tacitly 

 suggests its origin as a secondary fenestration in the body of 

 the hyoid. He considers the great lateral expansion of the hyo- 

 branchial skeleton of both Xenopus and Pipa as a derivative of 

 the first and second branchial arches, and the thyrohyal as formed 

 from the third and fourth. 



Cope (7) copies Parker's figure of the hyobranchial skeleton of 

 Xenopus, and gives a new interpretation to the parts, the lateral 

 wing being considered as derived from the first, and the thyrohyal 

 from the second branchial arch. The paper is, however, marred 

 by contradictory statements, and the views expounded in the text 

 do not accord with those expressed by the figure. G-rouberg (18) 

 furnishes outline text-figures of the hyobranchial skeleton of 

 Xeiiopus and Fipa (p. 636), and several excellent illustrations 

 of the larynx of both sexes of Pipa (Taf . 38. figs. 10-20). He 

 pays most attention to the larynx of the male, and treats ' of 

 the intrinsic laryngeal muscles of this sex alone. He regards the 

 ivlole of the floor of the larynx of Pipa as derived from the 

 branchial skeleton, and compares it (p. 635) with the cartilago 

 thyreoidea of mammals. Wilder, in his admirable paper on the 

 Amphibian larynx, devotes a couple of pages (42. pp. 291-292) to 

 the hyobranchial and laryngeal skeleton of the Aglossa, and 

 gives four figures (Taf. 21. figs. 58-61) of these structures 

 in Xenopus. He refers also to the laryngeal musculature of 

 this genus. Unfortunately his observations on the Aglossa 



