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region. Here, therefore, the innervation clearly proves 
nothing, and it may at least be doubted whether it proves 
any more in the case of the Elasmobranchs. We refer 
now purely to neurological evidence, and are of course 
aware that the supposed migration of the Elasmobranch 
fin is alleged to be supported by ontogeny also. 
Stannius (op. cit.) makes several references to the 
spinal nerves of the Plaice, and he quite realised the 
morphological value of the anterior extremity of the dorsal 
fin, since he carefully distinguishes between the forward 
extension of mixed spinal nerves over the roof of the 
cranium, and the sensory dorsal branches of the cranial 
nerves themselves. His work also contains a figure of the 
anterior spinal nerves of the Plaice (Taf. iv., fig. 1). 
4.—Tnr Symparuetic Nervous System (Fig. 26). 
Owing to the impossibility of satisfactorily dissecting 
the anterior portion of the sympathetic, we plotted it out 
from the same series of sections as were used in the case 
of fig. 25. As it is drawn to the same scale, the two figs. 
may therefore be compared. Our examination of the 
sympathetic commenced at the sixth vertebra, and behind 
the seventh spinal nerve. It is described from behind 
forwards, right side first. 
The sympathetic cord may be conveniently divided 
into two parts, which we will call the cranial sympathetic, 
associated with the skull and cranial nerves, and the 
spinal sympathetic, associated with the vertebral column 
and spinal nerves. In each portion, the ganglia are 
numbered separately from before backwards. 
At the sixth vertebra the sympathetic is situated 
laterally below the centrum and the transverse process. 
It here sends a short Ramus communicans to the ventral 
ramus of the seventh spinal nerve (com. vi.), which 
