1895.] AITATOMY OF PIPA AMEMCAKA. 835 



of the forearm required by so purely swimming a creature as Pipa, 

 its place having been gradually taken by another muscle more 

 fitted by its place of origin to bring about those movements. 



A remarkable resemblance between Pipa and Dactylethra is 

 afforded by the peculiar arrangement of the latissimus dorsi muscle 

 in the two genera. Dr. Maurer ' has described and figured in Dacty- 

 lethra an " abdominal " portion of the latissimus which is quite 

 as extensive as in Pipa. From the figure (fig. 10) which illustrates 

 this I infer that the transversely running part of the muscle is 

 also present. It is possible, of course, that the resemblance is one 

 due to a similar environment, for Dactylethra is quite as aquatic 

 in its habits as is Pij^a. On the other hand, there is some evi- 

 dence that the likeness is one indicating a deeper-lying affinity ; 

 for Maurer points out that in Ceratophrys the abdominal portion 

 of the pectoral is feebly developed, while in Dactylethra it is large 

 as in Pipa ; in both of these genera the fore-limbs are largely 

 used, and the fore-limb of Ceratophrys is much stouter than that of 

 Dactylethra; so that on a prion grounds it might be expected that 

 the pectoral of the former would be larger. 



The same kind of argument might apply to the latissimus, which 

 is the antithetical muscle to the pectoral. There are therefore 

 some grounds for believing that the resemblance between Pipa 

 and Dactylethra in this matter are resemblances of genetic import- 

 ance. The great extent of this muscle in these two genera of 

 Anurous Amphibians is suggestive of the Mammal to which it has 

 been said that the myology of the Anura bears more resemblance 

 than the Urodela. 



The rhomboideus (or retrahens scajndce), which in Eana guppyi 

 arises almost entirely from the spines of the vertebrae — a small 

 portion only springing posteriorly from the tendinous inscription 

 of the extensor dorsi communis — and not from the transverse 

 processes as in Bana esculenta, is totally absent in Pipa. To the 

 under surface of the scapula are attached three muscles, which 

 Ecker terms the transversi scapulares ; they are all three present 

 in Pipa. 



So, too, are the levator anguli scapuhe, the sternocleido-mastoid^ 

 and the protrahens scapidce, which attach the scapula to the 

 head. 



The infraspinatus arises, as in the frog, from a large portion o£ 

 the dorsal surface of the scapula ; a few fibres, however, take their 

 origin from the fascia which Ues between the scapula and the 

 head. In the frog a straight line ruled across the scapula would 

 indicate the sharply marked anterior boundary of the origin of the 

 muscle. In Pipa the corresponding line is V-shaped, the muscle 

 being really in two parts. The anterior half of the muscle, which 

 extends further beyond the edge of the scapula than in Bana, 

 crosses over the posterior portion near to the insertion and narrows 

 rapidly to a thin tendon which is inserted in a line with, but inde- 



' " Die ventrale Eumpfmuskulatur der anuren Amphibien," Morph. Jahrb. 

 1895. 



