V2 MB. W. G. EIDEWOOD ON THE HYOBEANCHIAL 



ligament (PI. 8. fig. 6, I) of the larynx o£ tlie male Xenojpus, 

 although the j)hysiological significance is probably the same. 

 The ligament in Pipa connects the anterior and posterior 

 portions of the basal plate, but in Xenopus the basal plate is not 

 subdivided, but is incorporated bodily into the constitution of 

 the larynx, while the ligaments arise from its anterior end. 

 Except in the ligamentous nature of the isthmus the hyobranchial 

 skeleton of the male Pipa does not diflier materially from that of 

 the female. 



The laryngeal walls are remarkably complete ; the roof (PL 9. 

 fig. 4) extends nearly as far forwards as the floor, and the notch 

 in its posterior border is but slight. The floor has a small but 

 deep notch behind (PI. 9. fig. 5) and, a short distance in front of 

 the notch, a pair of small fenestras ; but beyond these it is one 

 expanse of bone. The greater part of the fioor is formed by the 

 flattened thyrohyals, which can be distinguished from the rest of 

 the bone by their yellower colour and closer texture. The two 

 thyrohyals actually touch one another anteriorly, and the mem- 

 branous area in the floor of the female larynx is here closed by a 

 narrow strip of ossified cartilage. Along the sides of the larynx 

 the junction of the cricoid and thyrohyal is marked by a very 

 conspicuous groove (fig. 6). The roof of the larynx is marked 

 by a cruciform area in which the ossification is less complete 

 than elsewhere. Grronberg (18. Taf. 38. fig. 11) represents this 

 in his figure as actually cartilaginous. 



Although Gronberg was unable to consult Henle's treatise on 

 the larynx, and had to remain content with the copies of the 

 figures of that work published in Eronn's ' Klassen und Ord- 

 nungen ' (20), he detected that Ilenle had confounded the dorsal 

 and ventral surfaces of the larynx of the male Pipa. Curiously 

 enough, Henle (19. p. 20 footnote) charges Breyer with doing 

 exactly the same thing. " Rudolphi hat die hintere und vordere 

 Flache verwechselt." As a matter of fact, Breyer's description 

 is correct and Henle himself was wrong. He had probably 

 observed that Breyer had described the thyrohyals on the wrong 

 surface of the female larynx, and became afterwards confused as 

 to the sex for which the description was erroneous. 



The two bronchi open together close to the median plane, by 

 a pair of apertures which occupy only a small proportion of 

 the posterior laryngeal wall. The bronchial cartilages are 

 arranged as in the female. The bronchi of Pipa have since the 



