346 FISHES 
CHAP. 
two contiguous lobes of lymphoid tissue which apparently 
represent a thymus. 
The Supra-renal Bodies.—The supra-renal bodies are organs 
of problematic function, which are present in the Cyclostomata, 
0es. 
ae 
B C 
Fia. 203.—Supra-renal and inter-renal bodies of Fishes. 
A, of Scyllium catulus ; B, of Acipenser sturio ; C, of 
Pagellus centrodontus. d.a, Dorsal aorta ; i, inter- 
renal body ; @.m, lymphoid portion of the mesonephros ; 
m, mesonephros ; mtn, metanephros ; ves, oesophagus ; 
sg.d, segmental arteries ; s7, supra-renal bodies; sy.n, 
sympathetic nerves. (From Swale Vincent.) 
and probably in all 
Fishes, and situated 
in close proximity 
to the kidneys. 
In the Cyclosto- 
mata  (Petromyzon) 
these bodies are re- 
presented by lobules 
of cells along the 
posterior — cardinal 
veins, and also by 
masses of peculiar 
cells = (“ chromaffin 
cells”) along the sides 
of the aorta and seg- 
mental arteries.’ In 
Elasmobranchs there 
are two distinct 
structures, the paired 
supra-renals and the 
inter-renals (Fig. 
203, A). The former 
are a series of pairs of 
segmentally arranged 
bodies, situated on 
the successive pairs 
of segmental arteries 
given off from the 
dorsal aorta. The 
two bodies which 
form the first pair are much larger than any of the others, and were 
formerly spoken of as “axillary hearts.” The inter-renal is usually 
a thin elongated “ ochre-yellow ” body, from which one or two lobes 
may be detached in front, and extends for a variable distance in 
' Giacomini, quoted by Swale Vincent, Journ. Anat. and Phys. xxxviii. 1903, 
p. 41. 
