i684 MR. F. E. BEDDARD ON THE [June 16, 



well developed and quite obvious in Rana and very greatly 

 developed in Brevicejjs. It is rather remarkable that Rhinoderma 

 not only shows no likeness to its ally Brevicejjs, but is even more 

 simple than Rana. For some distance in front of the end of the 

 ■obliquus externus the obliquits internus becomes obvious, its fibres 

 running at an angle with those of the externus. These fibres end 

 .at the edge of the sternohyoideus just as the fibres of the obliquus 

 externus end at the edge of the same muscle and of the rectus 

 abdominis further back. This ending, however, is apparent rather 

 than real. When the rectus is cut across, the obliquus externus is 

 seen really to end abruptly at its outer boundary. On the other 

 hand, the obliquus intemus anteriorly dips into the body and 

 forms a portion of the anterior paitition between the neck and the 

 trunk in a way which will be described immediately in connection 

 with the transversus portion of the obliquus internus complex 

 which was originally compared by Huxley to the Mammalian 

 diaphragm, and which I have named accordingly in the following 

 paragraph. 



The diaphragmatic muscle. — This muscular sheet arises as is 

 usual among the normal Batrachia Salientia — that is, the muscle 

 has not the large extent and backwardly prolonged origin that it 

 has among the Pelobatidse *. It overlaps the kidney on its way 

 to be insei-ted on to the oesophagus, which shows the enormous 

 ■extension of that visciis forwards, upon which I comment else- 

 where in this paper t. The muscle is entirely inserted on to the 

 oesophagus from the point where the latter enters the pleuro- 

 peritoneal cavity up to nearly its junction with the stomach. The 

 muscle also shares in the formation of the anterior wall of the 

 pleuroperitoneal cavity ; for it merges completely into the 

 obliquus internus, the two meeting (though the exact line of 

 junction cainiot in the least be distinguished) at about the centre 

 of the concave wall which they together form and which bounds 

 the pleuroperitoneal cavity anteriorly, as has been said. It is 

 difficult to say for this reason whether the muscle does or does not 

 supply fibres to the root of the lung. In any case strands of the 

 obliquus internus end upon the root of the lung. 



Pericardial Mttscle. — In the Common Frog a portion of the 

 obliquus internus has been described as having the following 

 relations to the pericardium and in the following words J : — " A 

 third portion [of the muscle in question], placed behind the 

 preceding, runs from the pharynx over the pericardium and is 

 attached to this nearly as far as the middle line, resting on the 

 sternum, the m. rectus and m. sternohyoideus. The lines of inser- 

 tion of the muscles of opposite sides form an angle open in front." 

 This is illustrated by a figure ; but neither the figure nor the 

 descinption appears to me to be clear. The portion of the obliquus 

 internus thus referred to is perfectly continuous with the rest of 



* Beddard, P. Z. S. 1907, p. 3i6, text-fig. 98 ; and p. 886. 



t Supra, p. 682. 



X Ecker's Proa-, Engl. Transl. p. 71. 



