1895.] ANATOMY OF PIPA AMEBIOANA. 833 



comparisons are more difficult. Its insertion on to the stomach 

 reminds us of Prof. Huxley's description ^ of a muscle in the 

 Crocodile which " arises on each side from the anterior margin of 

 the pubis ; and its fibres pass forward, diverging as they go, to be 

 inserted into the ventral face of the posterior part of the peri- 

 cardium and into the ventral and lateral parts of the fibrous capsule 

 of the stomach." 



More important is the comparison with the frog, in which there 

 is a muscle embracing the oesophagus, the so-called diaphragm. 

 This is figured by Howes in the ' Atlas of Biology,' and described 

 by Ecker as a part of the conjoined obliquus intemus transversus ; 

 it arises, however, from the transverse process of the anterior 

 vertebrae, but may still represent the anterior portion of the 

 muscle described and figured here in Ptpa. It is, however, 

 perhaps more likely that the diaphragm of Rana is represented by 

 the termination of the obliquus internus lettered a in my diagram 

 (woodcut, fig. 2) of Pipa. If it be possible to compare the rudi- 

 mentary diaphragm of Rana with that of the Mammalia, it seems 

 even more possible in the case of Pipa. For in Pipa the diaphragm 

 is formed by a dorsal and ventral set of muscles ; there is a com- 

 plete ring of muscles as in the Mammal. 



The female frog which I dissected bore a number of young upon 

 her back. I examined one of these, a fully-formed frog of about 

 half an inch in length, in order to ascertain how far the various 

 structures described above were visible. The anterior end of the 

 young frog was cut into a series of longitudinal sections. I found 

 that the lungs hung freely in the body-cavity after their emergence 

 from the thoracic region ; there was no trace whatsoever of any 

 muscular or other attachment to the parietes. On the other hand, 

 that section of the diaphragm which I have described above as 

 shutting off the heart and pericardium from the abdominal cavity 

 was present. So far, therefore, as one is at liberty to draw in- 

 ferences from the order of development of various structures, 

 the muscular fascia which spreads out over tlie lungs is a newer 

 structure and perhaps conditioned by the special needs of Pipa, 

 which is, as is well known, more purely aquatic in its habits than 

 are many other Anurous Amphibia. 



§ Myology. 



The muscular anatomy of this Amphibian has been to some 

 extent described by Mayer with an illustrative figure. I have 

 endeavoured to supplement his account with some additional 

 details. The animal was dissected side by side with an example 

 of the large Rana guppyi from the Solomon Islands, which agrees 

 in its myology with Rana esculenta, excepting in some small par- 

 ticulars noted in the course of the following description. The 

 English translation by Haslam of Ecker's ' Anatomy of the Frog ' 

 has been my guide in comparing the muscles of the two animals, 



I Ibid. p. 568. 



