AORTIC LIGAMENT IN INDIAN FISHES. 



65 



resting on — or, more correctly, supported ])y — regularly arranged 

 white round masses of connective tissue (text-fig. 1, lig.). At 

 first sight these round masses look like adipose tissue, but on 

 closer inspection they are found to be aggregations of adventitia 

 tissue which form the outermost layer of the wall of the aorta. 



Text-figure 4. 



Text-fig-. 3. — Fseudeutropius garna (X 15). Transverse section of the aorta through 

 the sub-vertehral region (A-B) of text-fig. 1. 



d.w., dorsal wall of aorta; con., sub-vertebral mass of connective tissue ; Jig., aortic 

 ligament; cav., cavity of aorta ; intima. 



Text-fig. 4. — Fseudeutropius garua (X 15). Transverse section of the aorta through 

 the sub-intervertebral region (C-D) of text-fig. 1, 



d.w., dorsal wall of the aorta ; con.', sub-intervertebral mass of connective tissue ; 

 n., neck or the thin suspensory fold of the ligament ; lig., ligament. 



Each of these round masses of connective tissue occurs beneath 

 the body of each vertebra and fits into a depression in the 

 centrum on its ventral side. In certain fishes, as in Laheo rohita 

 and Catla huchanani, these depressions in the centrum acquire 

 the form oY deep notches ; and in such cases the masses of con- 

 nective tissue have to be carefully scooped out from the cavities 



Pkoc. ZooL. Soc— 1920. No. Y. 5 



