1907.] OP A FROG OF THE GENUS MEGALOPHRYS. 337 



(I am not quite certain as to B. agua) ; its fibres are inserted on to 

 the transverse processes of vertebra3 4 to 7 inclusive. It is from 

 the fourth vertebra in these species that the oesophageal and lung- 

 muscles arise (see below, p. 346). In Rana also it is from the 

 fourth vei'tebra. 



The resemblance between Btbfo and Ceratophrys in the muscles 

 now under consideration, particularly in their feeble develojoment 

 as compared with the corresponding muscles in some other genera, 

 might be put down to similarity of habit. For Ceratoplirys is 

 emphatically a ' toad ' in its terrestrial habits and lethargic life. 

 1 find, however, that there is a close likeness in respect of these 

 various structures between Ceratophrys and Leptodactylus which 

 is important in view of their inclusion in the same family Cysti 

 gnathidse by some systematists. T have examined two individuals 

 of Leptodactylus hexadactylus, which agree entirely in all the 

 sti'uctural features to be ref ei-red to immediately. A considerable 

 portion of each ilium is left perfectly free of muscle. As in 

 Ceratophrys, but not in Bufo, the anterior extremities of the ilia 

 do not reach as far as the transvei-se process of the eighth vertebra ; 

 they extend beyond them in Bufo. The ilio-coccygeal commences 

 some little way down the ilium and gives off slips to the transverse 

 processes of vertebrae 4 to 8 inclusive, and the oiigin of the lung- 

 mviscle is confined to the fourth vertebra. 



There is not, in fact, much diff'erence in these particulars 

 between LejUodactylus and Rana. For though in the lai-ge Rana 

 guppyi the ilium is well covered by the ilio-coccygeal muscle, this 

 is not the case with Rana tigrina. And the well-marked tendi- 

 nous intersections of the muscle in the lai-ger Rana are not seen 

 in the smaller species, which thus resembles Leptodactylus. In 

 Ceratophrys the modifications as to these muscles have gone still 

 further, and it is perfectly clear from the figures (text-figs. 94, 96) 

 that that genus shows marked, though in reality superficial 

 differences from other Frogs, which may perhaps, in view of its 

 likeness to Bufo, be looked upon as adaptive. It is, however, 

 perfectly clear that Megaloplivys and Pelohates, though diftering 

 from each other in various details, are on the whole much more 

 difierent from the other genera treated of here than are any of 

 those genera among themselves. 



§ Muscles of the Veoitral Surface. 



In the sternal i-egion of Megalojyhrys nasuta the following- 

 muscles are displayed when the skin is removed : — (1) Pars 

 abdominalis of Pectoral ; (2) Pars sternalis of Pectoral ; (3) Pars 

 epicoracoidalis of Pectoral ; (4) Pars epistemalis of Deltoid ; and 

 (5) Pars scapiilaris of Deltoid. As contrasted with Rana, the 

 most salient difference shown in this dissection is the very large size 

 of the episternal head of the deltoid, which is as large as, and of 

 course longer than the scapular portion, and together with the 

 epicoracoidal head of the pectoral completely hides from view the 



