1908.] 



BATRACHIAN RHIXODERMA DARWINI. 



685 



the muscle (I distinguish the oesophageal muscle as distinct) which 

 forms the internal sheet of the abdominal musculature. The 

 region, however, now vinder consideration is that portion of the 

 obliquus externus which is uncovered anteriorly by the obliquus 

 externus. The latter muscle ceases at about the level of the apex 

 of the heart, its most anterior region being separated off as the 

 omo-abdominal muscle. In front of this the lateral wall of the 

 pleuroperitoneal cavity is formed by the obliquus internus only, 

 and this muscle (of course with its lining peritoneum) limits the 

 abdominal cavity antero-laterally and constitutes the muscular 

 wall of the " cervical limiting membrane of abdominal cavity " 

 (Keith *). Yentrally this section of the internal oblique muscle 

 becomes divided into two insertions. The most posterior ends in 

 a delicate aponeurosis which passes outside of the sternohyoid 

 muscle and is attached to the coracoid and sternum. The anterior 



Text-fig. 145. 



Ollr 



-Ant.aid. 



A portion of the musculature of the ventral surface of Mhinoderma darivini. 



Ant.abd. Anterior abdominal vein. H. Heart, i.t. Tendinous intersection of 

 rectus abdominis. Ohl. Obliquus externus. P. Pericardial muscle. Feet. 

 Pectoralis. R. Rectus abdominis. St.h. Sterno-hyoid. 



section of the muscle is attached by aponeurosis to the pericardium 

 quite anteriorly (in the region of the emergence of the conus 

 arteriosus), and to the roots of the lungs. The whole of the 

 ventricular region of the pericardium is quite free from any 

 muscular insertions. This fact (the freedom of the whole 

 ventricular region of the pericardium from connection with the 

 obliquus internus) is not plainly shown in the figure of Gaupp 

 reproduced by Keith f. In addition to the insertion of obliquus 

 internus fibres upon the anterior and lateral regions of the peri- 

 cardium, Dr. Keith has remarked that some of " the deep fibres 

 [of the rectus abdominis, behind the sternohyoid] may end on the 



* J. Anat. Phj's. xxxix. 1905, p. 24-1, tig. 1, explan. of figure, 

 t Log. cit. p. 259, fig. li. 



