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the region of the island. The second — the vena cerebralis media (Figs. 

 9, 10 and 13) — arises at the anterior juncture of the vena capatis lateralis 

 with the anterior cardinal vein between the fifth and seventh nerves. The 

 third — the vena cerebralis posterior — arises from the posterior part of 

 the vena capatis lateralis with the internal jugular behind the otic 

 vesicle and enters the embryonic skull through the jugular foramen 

 (Fig. 12), and ultimately becomes the transverse sinus. From this simple 

 reptilian stage the mammalian is formed, and in man but little must be 

 added to, and but little subtracted from, the general plan. 



The anterior end of the anterior cardinal vein remains in large part 

 en the medial side of the fifth nerve in the human embryo and is ulti- 

 mately transformed into the cavernous sinus. From the earliest stages 

 the ophthalmic vein enters this sinus as is shown in all of the embryos 

 studied. Although I have no evidence regarding the development of 

 intercavernous sinus, it is easy to understand its development by branches 

 from the cavernous sinus growing to encircle the hypophysis, and then 

 to unite, thus forming a plexus around it. So also by an extension of 

 the cavernous sinus forwards the spJieno- parietal sirius must be formed. 

 In the early embryos the anterior cardinal vein or the portion which 

 forms the cavernous sinus is extended forAvard to form the vena 

 cerebralis anterior, which ends in the bilateral superior sagittal sinus as 

 shown in Fig. 3. With this the veins from the region of the island 

 communicate as shown in F]g. 10, the basal portions of which are evi- 

 dently retained to form the middle cerehral (superficial Sylvian) vein. 

 So also the superior sagittal sinus, the superior and inferior petrosal 

 sinuses and the vena capatis lateralis are directly continuous with the 

 cavernous sinus from their beginning. 



I have spoken enough about the vena capatis lateralis above, and wish 

 only to add its relation to the permanent brain sinuses in man at this 

 point. It may be defined as that portion of the anterior cardinal vein 

 which is transferred to the lateral sides of the cranial nerves extending 

 in the human embryo from the fifth to the twelfth cranial nerves, being 

 directly continuous in front with the anterior cardinal vein, or better 

 the cavernous sinus, and behind with the internal jugular vein. This 

 vein is clearly outside of the skull, leaving it between the fifth and seventh 

 nerves (Fig. 12), and then communicating with the internal jugular. 

 It is this vein which Kolliker believed to be the external jugular, and 

 apparently confirmed Luschka's notion regarding the relation of the 

 external jugular vein to the brain sinuses. It certainly does leave the 

 skull along the root of the seventh nerve, a line in common with the so- 

 called foramen jugulare spurium, but it disappears long before 



