George L. Streeter 5 



noitl lies external to it, and separates it from the dura proper. In the 

 intervening spaces the pia becomes thinner and web-like; here the 

 eminentise ventrales bulge forward and along their lateral border give 

 oft' the ventral nerve roots which pierce the pia jnst ventral to the liga- 



VENTRAL 



DORSAL 



Lig. long, lac. 

 Lig. long, venti 



Eminenlia ventr. 



Sulc. Irans 



Radix venlr. 



X. 



Fiss. long, venlr — 

 (Comissura ant) 



Lig. Irans. ventr 

 f area relic. 

 PIA 



[ area ligam, -■ 



Fiss. long venlr. 



0' 



I!! 



sulc. dors, med 



-^^ — Radix dors. 



- Funic, dors 

 5inus rhomb. 



5ulc, lal, 

 Sulc. dors.lat. 



■ Sulc. dors, med. 



Fig. 2. Ventral and dorsal surfaces of the lumbo-sacral enlargement of the 

 ostrich spinal cord, enlarged to IVs natural size. The pial sheath has in part 

 been stripped off in order to show the eminentise ventrales. X indicates 

 the situation of one of the nuclei marginales majores. 



.menta long. lat. Strong fibrous processes, Ugamenta denticulata, ex- 

 tend also lateral from the ligamenta long. lat. to the dural sheath and 

 thus render further support to this region of the cord. See Fig. 5. 



