371 
Nachdruck verboten. 
On the Disappearance of the transient Nervous Apparatus in the 
Series: Seyllium, Acanthias, Mustelus and Torpedo. 
By J. Brarp, University of Edinburgh. 
In the following lines an interesting and curious problem is enun- 
ciated and a solution, which was not found without much pondering 
over the puzzle, attempted. 
The notes concerning the apparatus in Scyllium, Acanthias, 
and Mustelus are taken from a large series and from a set of sketches 
prepared for Pt. II of my work on “a Transient Nervous Apparatus 
in certain Ichthyopsida”. 
It was anticipated that by now the second part would have been 
in the press, but the new results regarding the yolk-sac and contents, 
and all the remarkable things which arose out of those!) have ne- 
cessarily delayed the completion of the work. Here it is not proposed 
to describe the finds at any length, but, merely, to sum up the general 
result in each case. 
In the development of Scyllium canicula there appears a trans- 
ient nervous apparatus of a very similar kind to that already de- 
scribed for Raja batis. It is almost as richly developed as in the 
latter, and most of the pictures already given for Raja batis might 
serve for the illustration of corresponding sections of Scyllium em- 
bryos. 
The total number of ganglion-cells in the trunk region is not as 
great in the latter as in the former, but this deficiency is, perhaps, 
made good by an increased number along the tail. 
Transient nerves occur, but they are much finer and less com- 
plicated in build than in Raja. Their origin and course are quite 
similar. The “peripheral” ?) elements of the system are also represented 
in Scyllium by ganglion-cells in the myotomes and other positions, 
exactly as in Raja. In fact, nothing has as yet presented itself, to 
alter the belief, that the transient apparatus of Raja is one typical 
of that of many Elasmobranchii. 
1) Vide “On certain Problems of Vertebrate Embryology”. Jena, 
G. Fischer, 1896. 
2) Peripheral as defined in Pt. I. 
