X Proceedings of the Association of American Anatomists 



transversimi. The epiph3-sis arises from the roof of the midbrain some 

 little distance posterior to the velum at a slightly earlier stage. At 15 

 mm. the paraphysis is a slender tube parallel to the velum and opening 

 just anterior to its lower extremity. The roof of the forebrain just 

 anterior to it has grown downward to a marked degree so that a very 

 marked angle has been formed in the roof of this part of the brain. The 

 epiphysis is attached to the brain by a short stalk which, however, con- 

 tains no cavity and the posterior commissure appears for the first time 

 just behind the stalk. From now on the paraphysis begins to give oif 

 lateral tubules. It lies in close relation to two vessels, one anterior 

 and one posterior. The velum grows rapidly backward nearly to the 

 hindbrain and another outgrowth arises from the roof of the fore- 

 brain just anterior to the paraphysis and extends downward and back- 

 ward towards the infundibular recess. The vessels in relation to the 

 paraphysis grow into these projections and form two choroid plexuses, 

 a superior and an inferior, between the origins of which opens the para- 

 physis. The choroid plexus of the lateral ventricles springs from the 

 base of the inferior plexus. The superior commissure appears first at 

 16.5 mm. In the adult the paraphysis extends forward between and 

 above the hemispheres. From its central cavity, a confused mass of 

 tubules are given off, which appear to anastomose to a certain extent 

 and each tubule is in intimate relation with a vessel, no connective 

 tissue lying between them. This is apparently a type of sinusoidal cir- 

 culation and the structure is of a glandular character. The choroid 

 plexuses are very extensive and surround the opening of the paraphysis. 

 They intermingle to a great extent with each other and extend backward 

 to the hindbrain. The epiphysis is a narrow tul^e extending forward 

 over the superior commissure and connected to the brain by a short 

 slender stalk. Its cavity is subdivided to a certain extent b}^ incomplete 

 septa. 



THE DEVELOPMENT OP THE CUTANEOUS NERVES OF THE POS- 

 TERIOR LIMB IN MAN. By Charles R. Baedeen. Department of 

 Anatomy, University of Wisconsin. 



The cutaneous nerves of the posterior limb in man first extend out to 

 the anterior, distal and posterior margin of the limb-bud and from tliese 

 margins they then grow over the ventral and dorsal surfaces of the limb. 

 The segmental distribution of the sensory fibers of the spinal nerves 

 which supply the limb described by Head, Sherrington and others, seems 

 to be due to the fact that each spinal nerve has a path of maximum 

 directness toward the margins of the limb bud at the period when the 

 sensory branches of the main nerves of the limb are given off. 



