1908.] OF THE BATRACHIAX GENUS IIEMISUS. 903; 



of the lymph-sac. When the dorsal part of the muscle now 

 nnder description is cut through by an incision running- 

 parallel with the long axis of the body, it can be plainly seen 

 to be a single thoug'h fairly thick layer of muscle. There is 

 no layer underneath it. There is, in fact, in this region, that is 

 along the entire back, but one obliquus muscle. There is, 

 however, a strong fascia covering the muscle dorsally. This latter 

 may really repre'sent the obliquus externus as well as a portion of 

 the rectus abdominis already described as being inserted upon the. 

 skin. For the muscle which I am now describing has, in spite of 

 the direction of its fibres, more in common vvith an obliquus 

 internus. When the fibres are traced ventralwards they are seen 

 to end in a digitate fashion on the sides of the body in a delicate 

 membrane. Anteriorly the muscle extends to within a very 

 short distance of the scapula, but not in the least touching it. 

 It is bounded, in fact, anteriorly by the origin of the depressor 

 mandibula?. It is interesting to notice how thoroughly this Frog 

 Hemisus differs from its ally Breviceps in the oblique muscles.. 

 In the latter they are both well developed and fleshy throughout. 

 In Hemisn,s the muscles are largely defective as muscular tissue ; 

 and on the ventral side there is only the delicate membranous 

 continuation of the obliquus. 



This sheet of the body-wall is partly muscular and partly forms. 

 a delicate membrane of connective tissue, in which no muscular 

 but only wavy connective-tissue fibres can be detected by the- 

 microscope. As to the latter tract, I shall presently mention it 

 in describing the rectus abdominis muscle. When the rectus is. 

 cut across, reflected in the middle region of the body, a delicate 

 membrane comes into view which underlies the rectus and is the 

 membranous part of the obliquus internus referred to. It is even 

 suggestive of an omentum, such is its freedom from the rectus. 

 It is not, however, attached to the viscera which it covers, save 

 here and there by an emergent blood-vessel. It extends all over 

 the body-cavity right back'to the neighbourhood of the bladder— 

 in fact, to the posterior boundary of the abdominal cavity. It is- 

 quite thin and transparent. It appears to me that this membrane 

 must be referred to the obliquus internus, since it is absolutely 

 continuous with a sheet of muscle laterally which can be nothing 

 else than the obliquus internus, as well as the muscular sheet 

 anteriorly which bounds the thoraco-abdominal cavity. _ 



The recUis abdominis in this Frog is much more like that of 

 Brevicejys than of RhivGclerma. For it has only one inscriptio 

 tendinea between its origin at the ]jubes and the inscriptio ten- 

 dinea to which the pectoralis abdominalis is attached. The fibres 

 too are arranged in a fan-shaped way like those of Breviceps, and do- 

 not run only in an anterior direction parallel with the longaxis 

 of the body as in Rhinoderma and many Frogs. In the middle 

 line of the body the fibres run postero-anteriorly ; laterally they 

 are quite obhque in direction. Furthermore, it will be noticed 



