70 ME. W, G. EIDEWOOD OIN" THE HTOBEAWCHIAL 



lamina superior pariter cartilaginea duo tamen exbibet ossicula 

 plana," etc. This error was exposed by Meckel in 1833 (28. 

 Theil vi. p. 451). It may be well to point out bere tbat, while 

 Henle describes the orientation of parts with the toad standing 

 on its hind legs in an erect, human position, Breyer and most 

 writers place the animal belly downwards. What, therefore, in 

 this paper is called the roof of the larynx, is the 'lamina 

 superior ' of Breyer, the ' dorsale Wand ' of Gronberg, and the 

 ' hintere Wand ' of Henle. Wilder (42) avoids the difficulty by 

 speaking of the ' pharyngeal' and ' cardiac' surfaces. 



The roofing cartilage of the larynx has a deep angular notch 

 posteriorly and an approximately semicircular one anteriorly. 

 The incisions are so deep that a median longitudinal section of 

 the larynx shows only a rery small extent of cartilage in the 

 roof (PI. 9. fig. 3, c). Into the anterior space there fits a thin 

 unpaired plate of cartilage, which overlaps the hinder portions 

 of the arytenoids. This plate (figs. 2 and 3, pc.) is probably to 

 be regarded as a dismembered part of the cricoid cartilage. It& 

 nearest representative, Henle points out (19. p. 43), is the small 

 cartilage similarly placed in some Chelonia, (see Henle, 19. Taf . 5. 

 figs. 28 and 29, /). Dubois (9. p. 181, and fig. 5) calls this 

 latter the procricoid, and the name may safely be extended to 

 the cartilage under consideration in PIjm. 



The arytenoid cartilages are rather larger in proportion to the 

 size of the larynx than in the female Xeoiopiis, and the process 

 (PI. 9. figs. 1 and 2, d) to which the tendon of the dilator muscle 

 is attached extends outwards considerably beyond the outer 

 margin of the thyrohyal ; whereas in Xeiiopus the whole of the 

 arytenoid is confined to the space between the two thyrohyals 

 {cf. PL 9. figs. 1 and 2, and PI. 8. fig. 3). The anterior parts 

 supporting the sides of the glottis are thin ; the posterior parts 

 underlying the procricoid, although touching one another in the 

 median line, are not massive as they are in XenojJus, nor do they 

 articulate by broad flat surfaces. A median section of the larynx 

 shows the existence of a firm fibrous mass (fig. 3, vc.) covered by 

 a thin mucous membrane, and attached to the mesial surface of 

 the arytenoid cartilage. Its posterior edge is free, and although, 

 the tissue is not as elastic as the vocal cord of tongued Anura, 

 there can be little doubt that the two structures are homologous. 

 It may be said of the male Pij)a and of both sexes of Xenopus,. 

 that vocal cords are absent, but this statement should be 



