952 REPORT—1896. 
Comparison of the Branchial Appendages of Limulus, Eurypterus, &c., 
with the Branchial Appendages of Ammocetes. Meaning of the 1Xth 
and Xth Nerves. 
We will first consider the posterior group—the VIIth, IXth, and Xth nerves— 
and of these I will take the [Xth and Xth nerves together, and discuss the VIIth 
separately. These nerves are always described as supplying in the fishes the 
Vig. 3.—Head Region of Ammoceetes, split longitudinally into a ventral 
and dorsal half. (Dorsal Half.) 
Appendages 5 Nerves 
TENTACULAR 
ym i-a 
TRABECULZ 
PITUITARY BODY 
‘OLD GSOPHAGUS 
HRRATED EDGE 
CILIATED GROOVE 
yu 5 
OPERCULAR 
Wit 
ist BRANCHIAL 
Ix 
2nd BRANCHIAL jf 
"il ATTA —== 
COT. em 
1 ? = " 
3rd BRANCHIAL Hy 
x? 
Ei 
4th BRANCHIA 
5th BRANCHIAL is 
x4 | 
6th BRANCHIAL |i 
x* 
SOMATIC MUSCLE 
7th BRANCHIAL SPLANCHNIC MUSCLE 
xs 
CARTILAGE 
MUCO-CARTILAGE 
muscles and other tissues in the walls of a series of gill-pouches, so that the respi- 
ratory chamber is considered to consist of a series of pouches, which open on the 
one hand into the alimentary canal, and on the other to the exterior. Sucha 
description is possible even as low down as Petromyzon, but when we pass to the 
Ammoccetes we find the arrangement of the branchial chamber has become so 
different that it is no longer possible to describe it in terms of gill-pouches, The 
