86 Journal of Comparative Neurology and Psychology. 



tuating the drawing downward of the more caudal pairs of nerves. 

 The young ostriches, as I hav^e observed them on the ostrich farms 

 of this State, appear to have necks very much shorter in pro- 

 portion to the length of the body than do the adult birds, and 

 in all probability the same is true for the emu. If this is true, 

 then during growth the cervical vertebrae must undergo a pro- 

 portionately greater gain in length than an}' below them, whicli 

 would explain the fact that the nerves of the upper third of the 

 cord are attached at angles slightly cephalad instead of caudad. 

 Another feature to be noted in the spinal nerves of the 

 emu is that the roots and beginning portions of the lower cer- 

 vical and the thoracic nerves pass from the cord dorsal ward to 

 their respective intervertebral foramena (see Fig. i ). This 

 differs from the course of most of these spinal nerves of the 

 mammals and means that this portion of the cord lies deeper 

 in the bony framework about it. The small neck nerves prop- 

 er are similar in this respect to the neck nerves of the mammals. 

 As the natural result of the dorsal direction of the nerves, the 

 nerve roots approach each other along the dorso-lateral as- 

 pect of the cord, instead of the lateral or ventro-lateral aspect 

 (see Figs. 3 and 4). 



J^Yg: 2. Lateral longitudinal or horizontal section of 20th .segment pas.sing 

 at level of central canal. D — dura mater; P — pia mater; Zty^ — Ligamentum 

 epidurale; Z//— ligamentum longitudinale laterale; Lh — ligamentum longitudi- 

 nale ventrale; /'/' — ventral root; Fi' — fila radicularia of ventral root; .S^'— sub- 

 stantia grisea; Cc— canalis centralis; 7\ww — nucleus marginalis minor; Se — seg- 

 mental enlargement; J/— level midway between nerves. X A- The parts were 

 outlined by camera. 



Fig. J. Sc and M. Transverse sections of 22nd segment. Se — taken 

 through segmental enlargement corresponding to level similarly indicated in Fig. 

 2; ./I/— taken midway between the enlargements of the adjacent segments at lev- 

 el similarly indicated in Fig. 2. Lh' — ligamentum longitudinale ventrale; 

 _fr — fila radicularia of both roots; other reference letters same as in Fig. 2. Out- 

 lined by camera. X 4- 



Fig. ^. Sc and A/ — Transverse sections of 17th segment. Taken at lev- 

 els corresponding to those of Fig. 3. Reference letters, drawing and magnifica- 

 tion same as in Fig. 3. 



that between birth and the adult stages the cervical vertebra; undergo an aver- 

 age gain in length of about 2^0 %, while the lumbar vertebra; gain about 450 «/,, in 

 length. 



