82 Journal of Comparative Neurology and Psychology. 



The spinal cord of such an animal necessarily presents fea- 

 tures of unique interest and preparations were made with the 

 intention of describing it. Meanwhile, however, the paper of 

 Streeter ('04) appeared giving a description of the spinal cord 

 of the ostrich and on comparison it was found that the spinal cord 

 of the emu, in its general features, is apparently so similar to 

 that of the ostrich that a full description of it was deemed un- 

 necessary. Streeter's desrcription of the one may be referred 

 to for the most part as a description of the other. 



This paper, therefore, may be limited to a few of the fea- 

 tures presented in the spinal cord of the emu not touched upon 

 by Streeter for the ostrich and to some further observations 

 upon one or two points less fully treated by him. 



In the lumbar enlargement alone Streeter mentions hav- 

 ing observed a segmented appearance ("neuromeres") in the 

 ostrich cord. He does not refer to such as present in other 

 localities and little more than mentions it in the lumbar region. 

 After noting a few of the general macroscropic features of the 

 emu cord, some attention will be given here to the appearance 

 of evident segmental enlargements in other localities, as well as 

 in the lumbar region. In this respect it may differ from the 

 spinal cord of the ostrich. 



Lying in the vertebral canal, the spinal cord of the emu 

 is surrounded by an epidural cavity which is somewhat larger in 

 proportion than is usual in the more commonly studied mam- 

 mals. The dura mater has an unusually smooth outer surface. 

 Between the nerve pairs of the adjacent segments it appears 

 thicker along the ventral and ventro-lateral aspects of the cord 

 than along the dorsal aspect, while at the levels at which the 

 nerves are attached it appears thicker along the lateral surfaces. 

 From a number of measurements, made later from stained sec- 

 tions, the thickness of the dura mater was found to vary from 87 ix 

 to 146 [X, withan average thickness of 113/^. The arachnoidea is 

 similar in proportional thicknesss and arrangement to that usually 

 found in the mammals. The pia, however, is relatively thick as 

 compared with that of the mammalian cord. It is well defined as 

 to its outer surface and so thick as to be easily stripped from 



