100 JOHN BEARD. 
These various branches have all received general names, some 
of which require alteration in view of the researches contained 
in this paper. The branch posterior to the cleft is called the 
main or posterior branch (Balfour), and post-trematic by Van 
Wijhe ; in this paper it will be spoken of as the post-branchial 
nerve. The branch in front of the cleft, viz. the pre-trematic 
of Van Wijhe I shall call the prz-branchial nerve. 
The Ramus pharyngeus of Van Wijhe will retain the same 
name when spoken of here. But now for the so-called dorsal 
branches, of all the general names this is by far the worst. It 
is true that the name has been employed by many distin- 
guished zoologists, Stannius, Gegenbaur, Balfour, Marshail, 
and Van Wijhe, and that therefore to propose a change, except 
for very weighty reasons, would be a very high-handed and 
arbitrary proceeding. However, it must be done, and on 
grounds to be afterwards stated. 
Though some of these various so-called dorsal nerves may 
come to occupy a dorsal position, still, as was first mentioned 
to me by Professor Dohrn, it is morphologically wrong to 
regard them as dorsal. Of the truth of this I have fully 
convinced myself, and hope soon to convince the reader also. 
I have, however, no means of knowing whether my reasons for 
rejecting the name are the same as Professor Dohrn’s. These 
branches will be described by the general name of supra- 
branchial. 
So much for a general view of the adult condition. A 
schema of the development in Elasmobranchii would be as 
follows. (This account is in accordance with my own researches, 
and contains some additions to the accounts given by my pre- 
decessors.) 
The nerve grows outwards and downwards from the neural ~ 
ridge towards the lateral surface of the head. In its course 
it lies directly under, but unconnected with, the epiblast. In 
the case of those nerves which are connected with gill-clefts, 
and are therefore typical, the nerve lies just over the cleft 
(fig. 50). All this is well known, and has been described by 
Balfour, Marshall, Van Wijhe, &c. 
