240 THE SALAMANDER 



oviducal veins from the posterior region of the oviduct. (For the 

 entry of the pelvic vein see under this vessel.) If the injection is good 

 it is usually possible to trace Jacobson's vein to the anterior extrem- 

 ity of the kidney, but its size in this region varies very much. It 

 may remain fairly large, and anastomose with the post-cardinal 

 vein, but more usually it tapers to an almost indistinguishable 

 thread. 



B. The Common Iliac Vein (v.il.com.). The blood from the hind- 

 limbs has, in all Amphibia, the choice of two courses. It may go 

 through the pelvic and abdominal veins to the liver, or it may enter 

 the renal-portal system and pass through the kidney to enter the post- 

 caval vein. It is to provide for this latter course that common iliac 

 veins exist. Each lies on the dorsal side of the pelvis just posterior to 

 the ilium and to N. spinalis 1 7, and dorsal to the common iliac artery 

 of the corresponding side, and forms what appears to be the direct 

 continuation of the V. ischiadica, but is marked off from this vessel 

 by the origin of the V. iliaca transversa and the entrance of V. 

 pudenda (see Figs. 62 and 6'^). The common iliac vein joins Jacob- 

 son's vein a short distance from the posterior end of the kidney and 

 usually a little to the ventral side of that organ. 



The veins of the hind-limb must^ of course, be regarded as commenc- 

 ing at the distal extremities of the digits. The blood from the toes 

 collects into the digital veins which lie along the sides of each digit, 

 and, near the bases of the metatarsals, enter a transverse vessel lying 

 across the dorsal side of the foot — the Arcus venosus dorsalis pedis. In 

 addition to the above-mentioned veins from the toes this arc receives 

 several tributaries from the extensor muscles of the foot and tarsus. 

 In turn it delivers its blood into three main vessels. Of these two are 

 superficial and pass along the tibial and fibular sides of the leg, 

 corresponding respectively to the NN. dorsalis pedis tibialis and 

 fibularis, while the third and largest vein is a deep vessel and courses 

 in the interosseal space between the bones of the leg in company with 

 the NN. dors, pedis intermedius and interosseus. It lies superficial to 

 the A. interossea and deep to the above-named nerves. Just proximal 

 to the knee these three veins unite to form a single large vein, which 

 passes along the posterior aspect of the thigh together with the 

 sciatic nerve. 



This is rather different from the condition found in the Frog, but 

 bears a much closer resemblance to Osawa's account of Crypto- 

 branchus. The difference may probably be accounted for by the 

 specialized nature of the hind-limbs in the Anura. 



A comparison with the fore-limb and with Osawa's description 



