skeletojSt AjStd I/Aetnx of xenopus and pipa. 73 



time of Breyer (4. p. 15) been known to be longer in tlie female 

 than in tlie male, but the difference seems to have been much 

 exaggerated. Grronberg (18. p. 638) puts the length of bronchus 

 of the male at 15 to 20 mm., and that of the female at 25 mm., 

 and my own measurements accord tolerably well with these. 



The arytenoids are even more remarkable than the rest of the 

 laryngeal skeleton. The glottis, which is small in proportion, is 

 situated quite at the front of the pillow-shaped laryns. It is 

 bounded by small arytenoid cartilages (PI. 9. fig. 5, ar.) which 

 are continued outwards and backwards as relatively huge bones 

 {ar.'), each provided with four articular surfaces and two pro- 

 cesses for muscle-attachment. The bulk of each bony mass has 

 the form of a rod with a very irregular warty surface. The rods 

 ■extend the full length of the laryngeal cavity: their posterior 

 €nds are bluntly pointed and lie over the bronchial apertures. 

 They are composed of a very hard and brittle bone, and when 

 broken across exhibit a central whiter and softer part. Their 

 extreme length is about 22 or 23 millim. "What renders these 

 rods the more remarkable is the fact that there is not the least 

 suggestion, anticipation, or foreshadowing o£ them in the female. 

 The posterior parts of the arytenoids of the female Pipa are 

 insignificant even when compared with those of the female 

 Xenopus. Henle has already figured and described * with great 

 minuteness the configuration of these bones, so that it will here 

 suffice to state that they articulate with one another by two 

 pairs o£ processes, one towards the dorsal and the other towards 

 the ventral side, and that each articulates by a large flat surface 

 with the roof (figs. 4 and 5, v), and by a ball-and-socket joint 

 with the floor of the larynx. As a consequence of these peculi- 

 arities of articulation the rods lie close up to the roof, and are 

 raised somewhat above the floor. The fibrous tissue which 

 occupies the position of the vocal cords is less conspicuous than 

 in the female, but the arytenoid cartilages are distinctly hollowed 

 out, and are thickened along those edges that bound the glottis. 

 Although there is a very sharp line of demarcation between the 

 cartilage and bone, the two are perfectly continuous and move 



* In referring to Henle's description it must not be forgotten that be had 

 confounded the dorsal and ventral surfaces, and tbat in bis figiu'es (19. Taf. 2. 

 figs. 16-20) tbe words ' Torn ' and ' binten ' must be transposed throughout. 

 In Mayer's earlier work (25- P- 541), where a less detailed description is given, 

 tbe orientation of parts is correct. 



