834 MB. F. B. BBDDABD Olf THK [DeC. 3, 



which show a number of divergences other than those indicated by 

 Mayer. 



Muscles of the Head, Trunh, and Fore-limb. 



The obliquus extermts was, as Meckel has pointed out, overlooked 

 by Mayer, who, however, curiously enough, figures it. It is only 

 found in the posterior region of the abdomen, where it covers 

 the pectoral and arises from the symphysis pubis and also from 

 the rhomboidal area, mentioned in connection with the abdominal 

 portion of the pectoral. 



The Rectus abdominis is in three portions ; one arises from nearly 

 the entire length of the femur, and has been confounded by Mayer 

 with the abdominal poi-tion of the pectoral. As a matter of fact, 

 it ends in a transverse band of tendon (a tendinous inscription), 

 from which the pectoral arises. Another small portion runs from 

 the symphysis pubis to the rhomboidal tendon already mentioned. 

 The third portion is deep of the others, and passes forward on 

 each side to the edge of the sternum. 



The obliquus internus is a well-developed muscle which has an 

 antero-posterior direction. 



The depressor mandibular differs from that of Rana in that it 

 arises from the skull itself and not from any fascia. 



The cucullaris is an oblong muscle (it is triangular in Rana 

 guppyi) ; at its insertion it overlaps the last muscle instead of being 

 overlapped by it as in Rana. 



The latissimus dorsi has a very remarkable arrangement, which 

 differs greatly from that of Rana guppyi ; in the latter it is a long 

 triangular muscle which arises from the middle line of the back 

 and runs nearly parallel with and over the hinder half of the infra- 

 spinatus to be inserted in common with it on the humerus. In 

 Pipa the function of the latissimus dorsi is largely assumed by 

 what I take to be the homologue of a portion at least of the 

 obliquus externus. The latter is a fan-shaped muscle corre- 

 sponding in shape and extent to the abdominal portion of the 

 pectoral on the ventral side of the body. The muscle arises partly 

 from the fascia covering the lateral abdominal region and partly 

 from the great long transverse processes of the sacral vertebrae. 

 It narrows to be inserted on to the humerus in common with the 

 infraspinatus and partly on to lower border of scapula. Where it 

 passes under the scapula it is joined by a delicate muscle con- 

 sisting of a few widely separated fibres lying in the fascia covering 

 the scapula. This I take to be the much-degenerated represen- 

 tative of the latissimus dorsi of Rana. It does not, however, 

 blend with the fibres of the external oblique, but ends at right 

 angles to them. It will be noticed, however, that the pull upon the 

 forearm, which is the resultant of these two muscles, would not be 

 widely different in direction from that exercised by the single latissi- 

 mum of Rana, This, at any rate, might well be the case were the 

 muscles equal in strength. I beUeve, however, that the decay of 

 the latissimus dorsi bears some relation to the different movements 



