64 



MR. D. R. BHATTACHARYA ON THE 



Before it. acquires an attachment with the bone, the ligament 

 pierces through the wall of the aorta close to the junction of the 

 last vertebra with the urostyle. 



The aortic ligament, as ali'eady mentioned, has no connection 

 whatever with the well-known " ligamentum longitudinale supe- 

 rius " (Hertwig *) which lies above the spinal cord, is attached 

 anteriorly to the exoccipital bones and posteriorly to the urostyle, 

 and is flattened dorso- ventral ly (text-fig. 2, D.lig.). 



Text-figure 2. 



D.lig. 



Transverse section tlirongli the caudal region of ISutropiichtliys vacJia 



(X 15). 



J). ?i^., dorsal ligament ; sp.c, spinal cord ; c.i^., connective tissue ; Zi^'., aortic 



ligament ; cav.a., cavity of aorta. 



2. The Gross Structure and Histology of the Ligament. 



Text-figures 3 and 4 will show that in transverse section the 

 ligament looks more or less oval in shape, being thinner dorso- 

 ventrally than from side to side. On opening the aorta from the 

 ventral side and soaking out the blood with pieces of blotting- 

 paper, the ligament looks like a white flat sheet of elastic tissue, 



* Dr. O. Hertwig, ' Handbucli der Entwickelungslehre der Wirbeltiere,' p. 450. 



