900 MR. F. E. BEDDARD ON THE [Nov. 26, 



on to the bony thyroliyal, the anterior slip of the muscle straying 

 only slightly if at all on to the body of the hj^oid, as figui-ed for 

 instance by H. H. Wilder*. On the other hand, I have already 

 pointed out that in Megalophrys nasuta the first of the three 

 slips of the petrohyoideus posterior arises mainly — and indeed I 

 believe I may say, after a reexamination, exclusively — from the 

 body of the.hyoid at its junction with the thyrohyal t. In liana 

 a small slip of the petrohyoideus posterior tertius is not inserted 

 with the mass of the muscle on to the thyrohyal but forms a part 

 of the laryngeal musculature. I could see that this was the case 

 with Rana giq^j^yi, where nearly the whole muscle appeared to be 

 inserted on to the thyrohyal, but a few fibres escaped beyond it 

 and appeared to be inserted onto the ligament binding the 

 posterior end of the thyrohyal to the cricoid ; I did not trace 

 them beyond this point t. In Megalo-phrys nasuta I have described 

 this muscle as passing beneath the end of the thyrohyal § {i. e., 

 beneath when the animal is examined in the ordinary position of 

 dissection). In reexamining the Frog I find that this is the case, 

 but that the muscle is not entirely inserted upon the thyrohyal. 

 In fact, the greater part of the muscle escapes the thja^ohyal and 

 is inserted close to the laryngeal apparatus, and only a part is in- 

 serted onto the inner end corner of the thyrohyal. "VVe have here 

 in fact conditions precisely the reverse of those sometimes found 

 in Rana, the major part of the petrohyoideus posterior tei'tius 

 being a laryngeal muscle. I may point out that this fact is of 

 some importance embryologically. For, as Wilder j| has shown, 

 the petrohyoideus in question is originally a continuous miiscle 

 reaching the larynx, part of it in Rana becoming later separated 

 as an intrinsic muscle. Furthermore, among the Aglossa it has 

 been shown by Ridewood ■([ that the third division of the petro- 

 hyoideus posterior (or rather the muscle believed to correspond 

 thereto) is a purely laryngeal muscle, having no connection with 

 the hyoid. Thus Megaloflirys nasida shows a distinct likeness 

 in this anatomical relation — though it is doubtless a small one 

 — to the Aglossa. These same peculiarities of the petrohyoid 

 muscles occur also in the other Oriental Pelobatidaj upon which I 

 am able to report in the present communication. The peculiarities 

 therefore cannot be held to be in any way characteristic of sex. 

 In Leftohracliium hasseltii (see text-fig. 239) the three posterior 

 petrohyoidei are visible as perfectly distinct muscles. The petro- 

 hyoideus posterior primus is in contact with the petrohyoideus 

 anterior. The petrohyoideus jDOsterior secundus is larger than it 

 and the following and last of the muscles, which latter passes 

 under the cartilaginous epiphysis of the thyrohyal bone. 



* Loc. cit. and fig. cit. 



t This does not appear to be the case with Felodytes. 



X According to Goppert's figure, however {loc. cit., fig. cit.) the whole of the last 

 jjetrohyoideus escapes the thyrohj'al and is a laryngeal muscle. 

 § P. Z. S. 1907, p. 339. 

 11 Loc. cit. p. 307. 

 ^ Journ. Linn. See, Zool. xxvi. 1897. 



