1908.] OF THE BATRACHIAN GENUS HEMISUS. 911 



cartilage fixed on to the ceratohyals and extending backwards in 

 Hemis'us to form a ventral hood over the hyoglossal muscle is 

 represented in other Engystomatid Frogs though to a less degree; 

 for I identify this cartilage with that termed " extra-hyal " by 

 the late Prof. W. K. Parker*. This anatomist has figured a 

 small piece of cartilage so named in Engystoma carolinense where 

 it caps the forward convexity of the ceratohyal. The same 

 structure is depicted in the same place exactly in I'omojyterna 

 hreviceps (? = Kana hreviceps). In another Frog, Pyxicephalus 

 rufescens ( = Rana rufescens), the extra-hyal cai-tilage is shown to 

 be much larger, extending for a long way down the ceratohyal ; 

 but there is nothing like the hood of Hemisus. In Calhda, how- 

 ever, nothing of the sort is figured. But the Engystomatid 

 Diplopelma ornatum differs from its congener D. berdmorei and 

 agrees with Engystoma in possessing this cartilaginous cap. 

 Phryniscus also seems to want this structure. 



The hyoglossus is a very thick muscle, as is usual ; it forms a 

 single muscle for the most part where it traverses the lower 

 surface of the body of the hyoid. But a distinct slip on either 

 side is quite distinguishable from the main body of the muscle, 

 from the very origin of the muscle from the posterior cornua of 

 the hyoid. The fibres of origin of the hyoglossus can be stripped 

 away from the shaft of the posterior cornvi, with which bone they 

 have no relation except at the very tip, where they arise con- 

 tiguous with the insertion of the peti-ohyoideus posterior (see text- 

 fig. 178, p. 906). The hyoglossus, in fact, merely covers ventrally 

 the shaft of the posteiior cornu ; it is not at all wrapped round it. 

 The j»ei5roAyo?cZet6s is shown in text-figs. 178, 179, & 180. The 

 most remarkable featxire about this series of hyoid muscles is 

 the insertion of the anterior part of the muscle upon the ventral 

 surface near the middle line of the basihyoid. This muscle divides 

 as will be seen, the insertion of the first from those of the second 

 and third portions of the sternohyoid (see text-fig. 179). The 

 last petrohyoid is attached to the tip of the thyrohyal and does 

 not extend beyond it on to the larynx. 



The origin of the sternohyoideus I am unable to describe fully. 

 But the greater part at least seems to be derived from the under 

 surface of the conjoined coracoids. Whether any of it is formed 

 as a direct continuation of the rectus abdominis I do not know. 

 In any case the muscle is divisible from at least very near to its 

 origin into three distinct slips, which run forwards in close contact 

 and as one muscle. Whether these three separate slips correspond 

 or not to the three muscles in Brevicefs, of which I have referi-ed 

 two to the sternohyoid and one to a derivative of the obliquus 

 which I have termed in that Frog " hyoabdominal " f, I am 

 uncertain ; but their insertion one after the other in both Frogs 

 is in favour of this comparison. Moreover, the origin of the 

 hyoabdominal in Bremceps^ a little way behind and to the outside 



* Phil. Trans. 1881. 



t P. Z. S. 1908, p. 12, text-fig. 2, Hij.abd., and p. 23, text-fig. 5, liyMd 



Proc. Zool. Soc— 1908, No. LVIII. 58 



