1908.] BATRACHIAN RHIXODERMA DARWINI. 683 



section immediately following upon the funnel) in Rhinoderma is 

 very short and quite straight, much shorter than is, according to 

 my experience, the rule among frogs. The funnel itselt is 

 attached sideways to the surface of the obliquus internus, where 

 that muscle forms the anterior wall of the abdominal cavity, and 

 is of an elongate form, the orifice being a comparatively narrow 

 and terminal slit. The lining membrane is grooved at the mouth 

 of the funnel. The oviducts open into the cloaca by a single 

 common orifice. 



§ The Musculature of the Ventral Surface. 



The rectus abdoyninis shows no great peculiai-ities of structure. 

 It has five divisions, visible when the skin is removed and no 

 further dissection made. These are divided by four inscrijDtiones 

 tendinese. This contrasts in the most marked way with Brevice-ps, 

 where there is but a single inscriptio tendinea. These are all 

 behind the sternum, where the muscle appears to end. The 

 anterioi- abdominal vein is visible from the last insci'iptio tendinea 

 up to just behind the sternum, where it dips down and dis- 

 appears from view. The abdominal section of the pectoralis 

 muscle arises from the first three poststernal masses of the rectus. 

 The sternal portion of the pectoralis is hardly distinguishable 

 from, a sterno-radialis anteriorly ; but the latter — if it exists 

 as a separate muscle — is quite plainl}^ divided off from the 

 adjacent slender head of the deltoid. The posterior part of the 

 pectoralis sternalis is distinct from the anterior region' in that it 

 comes closer to its fellow of the opposite side in the middle line 

 than does the anterior part of the same muscle. 



The ohliqui externus et intermts have not the exti^aordinarily 

 complicated and specialised disposition of their bundles that I 

 have described in Breviceps verrucosus* . The obliquus extermts is 

 a tolerably stout muscle the fibres of which run at right angles to 

 the long axis of the body in the ordinary way, and which forms as 

 usual a continuous sheet covering the sides of the body. Opposite 

 to the second inscriptio tendinea of the rectus abdominis it is 

 overlapped by the pectoralis abdominalis, and in this region arises 

 (or is inserted) fi'om that muscle, or rather from the septum 

 between the two. In front of this area of overlap the obliquus 

 externus is seen — when the here superjacent pectoralis abdominis 

 is dissected away — to end abruptly at the septum between itself 

 and the several compartments of the rectus abdominis. The 

 fibres of the two muscles where they thus nearly come into 

 contact are absolutely at right angles. Anteriorly and much at 

 the same point, or i-ather along the same line, as in the Common 

 Frog the obliquus externus ends definitely in a straight anterior 

 border. There is not, however, in lihinoderma darwini any trace 

 that I could discover of an omo-abdominalis muscle, such as is 



* P. Z. S. 1908, p. 22. 



