NERVOUS SYSTEM. VERTEBRATA. 507 



Membranes of the Spinal Cord. 



D. 806. A section of the vertebral column, with the spinal cord 

 and its membranes, of a Basking Shark (Selache maxima). 

 The neural canal is lined by a thin fibrous membrane the 

 outer, perichondrial layer of the dura mater. The space 

 between this layer and the cord is occupied by loose tra- 

 becnlar tissue forming the deeper parts of the dura, and 

 giving support to a network of blood-vessels. The cord is 

 surrounded by a close-fitting pia mater. 



D. 807. Part of the spinal cord of a Calf (Bos taurus). The 

 dura mater has been removed except at the sides of the 

 upper part of the specimen. Upon the ventral surface of 

 the cord the arachnoid membrane has been longitudinally 

 divided and reflected, exposing the pia mater closely ad- 

 herent to the cord. The cut edge of the pia can be seen 

 on either side of the ventral longitudinal fissure at the upper 

 end of the specimen. 0. C. 1365 c. 



D. 808. A portion of the spinal cord of Man. The dura mater 

 has been removed from the dorsal and ventral surfaces, 

 exposing the subdural space and arachnoid membrane. 



0. C. 1378 B. 



