Hardestv, spinal Cord of the Emzi. 89 



The following features should be mentioned in which the 

 spinal cord of the emu differs from that of the ostrich, as de- 

 scribed by Streeter: 



1. The ostrich is given 51 pairs of spinal nerves or 51 

 segments in its spinal cord. Each of the specimens of emu 

 here studied had but 48 segments. 



2. While the sinus rhomboidalis in the dorsal aspect of 

 the lumbar enlargement is very evident in the emu cord it is 

 not quite so wide relatively as Stkeeter shows it to be in the 

 ostrich. 



3. The entire length of the spinal cord of the Emu from 

 the point of the calamus scriptorius to the end of the conus 

 medullaris was in one specimen 87 centimeters and in the oth- 

 er 90 centimeters. Practically the same measurement gave 

 Streeter 81 centimeters for the ostrich. He mentions how- 

 ever that his specimen was a young one. 



4. To the unaided eye there was no evidence whatever 

 of a distinct cervical enlargement in the spinal cord of the emu. 

 Streeter indicates an enlargement in the ostrich, evident in 

 the gross appearance. 



According to Furbinger ('88) the 17th to the 21st seg- 

 ments of the ostrich cord correspond to the region of the cer- 

 vical enlargement of the higher veitebrates. In the emu, as 

 in the ostrich, the smallest part of the cord is in the neck prop- 

 er — about the first twelve segments. This is to be expected 

 from the fact that for the slender neck the inervation required 

 of these segments must be small. At the i6th segment in the 

 emu there begins a perceptible increase in the general diame- 

 ter, in the middle of the 8th segment both the lateral and dor- 

 so-ventral diameters being 5 millimeters, while in the middle of 

 the 17th segment, the diameter was nearly 6 millimeters. From 

 the 1 6th segment a gradual increase continued till at the 22nd 

 segment the general diameter became 7 millimeters. From the 

 22nd to the 27th segment, instead of a decrease there was an in- 

 crease though more gradual than before. At the 27th segment the 

 increase toward the lumbar enlargement began to show and at the 

 29th segment the increase became more sudden. At the 32nd 



