1908.] OF THE BATRACHIAN GENUS HEMISUS. 895 



The latissiimos dor si is a large muscle, the origin of which 

 commences some way behind the scapula and extends forward to 

 a point about on a level with its posterior border. It arises from 

 the middle line of the back and underlies the fascia dorsalis which 

 is closely adherent to it. It should be mentioned in considering 

 this mviscle that the humerus is not free from the body. It is 

 closely connected with the fascia covering the body and a strongish 

 band connects the fascia dorsalis with the very elbow. This state 

 of affairs must necessarily, one would suppose, have influenced 

 the adjacent musculature. In any case, the latissimus dorsi 

 blends early with the infraspinatus, and indeed it is difficult to 

 distinguish between the two muscles anywhere. The conjoined 

 muscles narrow rapidly to form a thick muscle a little way from 

 the insertion on to the humerus. 



The cucullaris is a very massive muscle and is attached up to 

 the very tip of the suprascapula, along its anterior border. 



When the latissimus dorsi is cvit and reflected I can find no 

 muscle compai-able exactly to the transversely running rhom- 

 boideus (or retrahens scapulae) of Rhinoderma. The position of 

 that muscle is occupied by fascia binding the supi-ascapula to the 

 middle line of the back, in which no muscular fibres can be de- 

 tected on dissection. The cutting and reflection of the latissimus 

 dorsi, and the fact that the suprascapula thus exposed is a narrow 

 plate of cartilage with a concave posterior boundary-line, brings 

 into view certain muscles connecting the transverse processes of 

 the third and fourth vertebras with the scapula and suprascapula, 

 which have received various names in Rana. 



Inasmuch as these muscles have not been described in the 

 large female Rana guppyi, w^here they are naturally peculiarly 

 clear, and in which Frog they appear to differ slightly from the 

 corresponding set of muscles in Rana escidenta, it will not be 

 useless to describe these muscles before proceeding to deal with 

 those of Heviisus. 



In Rana giqypyi the muscles in question, which obviously 

 resemble, as has been pointed out, the serratus group of muscles of 

 higher animals, can be divided into two groups : — those which are 

 inserted on to the under surface of the suprascapula and those which 

 are inserted on to the under surface of the scapula. The direction 

 of the two sets of muscles is totally different, and their course 

 indeed lies nearly at right angles. The broad cartilaginous edges 

 of the suprascapula nearly completely cover this system of 

 muscles. The group which are inserted on to the suprascapula 

 consist of four muscles, of which one, the rhomhoideus, has been 

 -already described by myself in this species *. 



The second is a large flat muscle arising from the free end of 

 the ti-ansverse process of the fourth vertebra, which I take to be 

 the retrahens scapidce of Ecker (with which therefore I was wrong 

 in identifying the rhomboideus in my description of Pipa quoted 



* Cf. memoir on Fij)a, P. Z. S. 1895, p, 835. 



Proc. Zool. Soc— 1908, Ko. LVII. 57 



