254 Royal Society • — 



cession form similar loops with distant nerves. In former communi- 

 cations to the Royal Society, the author has shown that the same 

 kind of arrangement exists in the spinal cord of Man and Mam- 

 malia. 



The second or transverse order of fibres are less numerous, and in 

 general less distinct than the last. They proceed from the middle 

 of each opposite root, and cross the cords directly ; hut some of 

 them, on reaching the opposite cord, turn round in both directions, 

 and run with its longitudinal fibres. In front of the first ganglion, 

 in which they are unusually distinct, a separate band unites the roots 

 which descend from the branches arising from the opposite crura of 

 the pharyngeal collar. 



The third order of fibres, or those distributed to the vesicular sub- 

 stance, spread out in all directions, but always — except in the lateral 

 layers or columns — beneath the superficial stratum. After nearly 

 fifty separate examinations, with all the resources of the microscope, 

 the author has not been able, in more than two or three instances, 

 to trace an undoubted continuity between the cells and nerve-fibres. 

 Fibres in abundance may be seen in connexion with the cells, but the 

 greater number of these are not nerve fibres. Nevertheless, there is 

 reason to believe that such a connexion does frequently exist, but is 

 obscured by certain peculiarities of structure. Still it is quite certain 

 that a vast number of fibres pass by or around the cells near their 

 origin, and many often appear to terminate in loops. 



Cephalic Ganfflion... — This rests on the commencement of the 

 pharynx, beneath the dorsal part of the third ring. Each lobe is a 

 pyriform sac, which is very thick and convex posteriorly, where it 

 is partially separated from its fellow by a deep notch. This convex 

 portion is opaque-white, and filled with a mass of semifluid granular 

 substance, and oval, round and pyriform cells, of various sizes, but 

 often very large. Some of the latter kind are exceedingly elongated. 

 The anterior half, by which the lobes are joined, is merely lined with 

 a lamina of cells, and only at its upper part, its under side having a 

 cell here and there. The interior of this portion is entirely fibrous, 

 and consists of a broad transverse commissural band derived from 

 the pharyngeal collar, and of fibres from the roots of the cephalic 

 nerves. Each cms of the collar enters its lobe on the under side. 

 Some of its fibres curve backwards to the convex vesicular mass ; 

 others ascend to — perhaps partly terminate in — the cells near the roots 

 of the cephalic nerves ; and the rest cross transversely as the broad 

 band, to be continuous in front of the notch with that of the opposite 

 crus. The cephalic nerves are attached to the ujjper part of the 

 ganglion. Many of their roots cross transversely with the crural 

 band, to form loops with those of the opposite lobe. Decussating 

 these, a considerable number run down the pharyngeal crus, and 

 enter the pharyngeal chain of ganglia through its first and second 

 roots, at least, — perhaps throvigh all, — and probably form loops with 

 the other set of branches of the crus. The remaining fibres of the 

 cephalic nerves spread through the vesicular substance, partly de- 

 scribing curves and undulations in the corresponding lobe, and com- 



