242 THE SALAMANDER 



be called F, poplitea^ and is soon joined by the V. circumflexa genu 



to form the F. ischiadka. 



The F. circumflexa genu is a short vessel joining the sciatic vein 

 almost at right angles just proximal to the knee. As stated above it 

 joins the V. lat. cruris, while it also receives twigs from the knee- 

 capsule and a longitudinal recurrent vessel^ which lies in the thigh 

 between the MM. pubo-tibialis and pubo-ischio-femoralis internus, 

 i.e. along the anterior border of the limb. This vessel drains the 

 adjoining muscles and also receives large cutaneous factors from the 

 skin covering that region (possibly to be regarded as the VV. cutaneae 

 femoris anteriores mediales). It is usually traceable towards the body 

 as a very fine vessel which finally enters the pelvic vein, or anasto- 

 moses with a small factor thereof. There is therefore a continuous 

 but ill-defined venous channel passing along the whole length of the 

 pre-axial margin of the hind-limb, corresponding with the V. brachialis 

 lateralis of the fore-limb, which is doubtless the homologue of the 

 V. femoralis lateralis (Osawa) of Cryptobranchus. The position of 

 this channel and the fact that it is the only vein entering the pelvic 

 loop from the hind-limb anterior to the ilio-femoral joint would sug- 

 gest that it is to be regarded as the representative, in the Salamander, 

 of the femoral vein, which otherwise is wanting. A second anasto- 

 mosis with the V. ischiadica occurs at about the middle of the thigh 

 by means of the V. circ. fem. med. (see below), and hence the vessel 

 may be called F. collateralis femoris (v.col.fem.). 



The F. ischiadica (v.is.). After its origin from the union of the 

 popliteal vein with the V. circ. genu, as above described, the sciatic 

 vein continues along the posterior aspect of the thigh and receives 

 the following factors. 



(a) Posteriorly, the F. profunda femoris posterior enters from the 

 MM. ischio-flexorius and pubo-ischio-femoralis externus and from 

 the overlying skin. The cutaneous factor is the F. cut. fem. medialis 

 (Gaupp). ^ 



(b) Mesially a pair of FF. circumflexae femoris mediales are received, 

 one passing dorsal and the other ventral to the femur. They are both 

 muscular factors draining the thigh muscles. The ventral one anasto- 

 moses with the V. collateralis femoris. 



At the level of the hip-joint, in what Appleton conveniently terms 

 the 'posterior groin', the V. ischiadica unites with the F. iliaca trans- 

 versa and F. pudenda to form the common iliac vein. The sciatic vein 

 thus forms the main vein of the thigh in the Salamander and carries 

 almost the whole of the blood from the limb towards the trunk, whereas 

 in the Frog (and in man and mammals generally) this function is 



