896 MR. F. E. BEDDARD ON THE [Nov. 2(5, 



which covers completely, and has to be dissected away to reveal, 

 the underlying hyoglossus. This same arrangement of the genio- 

 hyoid is quite plain in Megaloiohrys montana and in Lejytohrachium 

 hasseltii, and apparently in Megalophrys nasuta. 



The hyoglossus in Xenophrys is an extremely stout muscle, 

 arising from the thyrohyals as usual. In cutting the muscle 

 through longitudinally in that part of it which lies on the body of 

 the hyoid, the muscle is seen to be separable into five superjacent 

 layers very plainly distinct from each other. The muscle does not. 

 run so far forwards along the floor of the mouth as in Rana, 

 and enters the tongue nearer the middle of that organ, which 

 is more attached to the floor of the mouth in the Pelobatidse 

 than in many other Frogs. This greater adhesion of the tongue 

 is perhaps connected with the spreading and greater extension of 

 the geniohyoideus. In respect of these matters, Leptobrachium, 

 shows no particular diflerences that I could discover from 

 Xenophrys. In Megalop)hrys montana (text-fig. 237) the only 

 difference appeared to me to be the much more marked subdivision 

 of the hyoglossus into rope-like strands at an earlier period than 

 in the other genera. It is important to notice that as regards the 

 two h3''oidean muscles that have been already dealt with, Pelobates 

 entirely agrees with its Oriental allies. In dissecting the muscles, 

 above described in the several species of Pelobatidaj, certain 

 diflerences are obvious in the point at which the hyoglossus dis- 

 appears anteriorly into the tongue from the floor of the mouth. 



In some species this point is more anterior in position, in others 

 more posterior. It is curious to remark that Xenophrys and Lepto- 

 hrachium offer the two extremes in jDOsition. The measurements 

 taken were as follows : from the middle of a line drawn connecting 

 the posterior (articular) extremities of each mandibular ramus 

 another line at right angles was drawn through the mandibular 

 symphysis ; this represents the length of the throat ; and the 

 point at which the hyoglossus disappears can be measured along 

 this line. The actual measurements in the types examined were 

 as follows : — 



Lensfth of 

 Throat. 



Xenojjhrys 22 mm. 



Megalophrys nasuta 42 ,, 



Megalophi'ys montana ... 22 ,, 



Leptohrachium hasseltii . . . 19 ,, 



It is also noteworthy that Leptohrachium and Megalophrys 

 montana are nearer together than any other forms, and that the 

 two Megalophrys are by no means identical. 



The hyoid cartilages of Megalophrys montana have been already 

 dealt with to some extent in this paper* as assisting to distinguish 



* Supra, p. 875. 



