168 MR. F. J. COLE ON THE STRUCTURE AjSD MORPHOLOGY OF 



and its double origin. A brief description of it is also to be foviud in Bonsdorff's 

 work published in 1846 (30), in which the two roots of the accessory lateral and tlieir 

 course through the parietal are described in " Gadus lota'' but little is said about its 

 peripheral distribution, whilst it is again renamed the " Ramus quartus s. lateralis 

 nervi trigemini." 



The description which Stannius gives of the accessory lateral nerves (1849, 199) is 

 concerned rather with their peripheral distribution, which, as far as the description goes, 

 is perfectly accurate. Gadus and other Teleosts are carefully described and figured, and 

 one may mention the figure of the former as being particularly admirable, whilst an 

 account is also given of the homologous nerves in the Siluroid Teleosts. In establishing 

 experimentally the somatic sensory nature of the nerves, and confirming the connection 

 which they have in some of the modern Teleosteans with the dorsal, pectoral, pelvic, and 

 anal fins, and also with the dorsal bi'anches of the spinal nerves, Stannius went a 

 long way towards the elucidation of their true morphology, which subsequent observers 

 failed fco follow up *. 



Hoffmann (1860, 100) briefly refers to the accessory lateral of Ci/pn'ims carpio as 

 the "dorsale Schadelhohlenast " (one of Stannius's terms), but only devotes a few lines 

 to it. He mentions the connection with the " trigeminus," and figures the posterior root 

 in Cyprinus. Swan (1864, 205) also mentions it in a few lines, points out the connection 

 of the dorsal ramus with the dorsal branches of the spinal nerves, and states that the 

 system is not represented in the Skate. He gives two figures which show the origin 

 and distribution of the accessory lateral nerves (which he calls " posterior branches 

 of the filth "), on of the brain and roots, and another illustrating its peripheral 

 distribution to the dorsal, j)ectoral, pelvic, and anal fins. I believe this figure, which 

 appeared in the first edition of this work, published in 1835, was the first to accurately 

 show the peripheral distribution of the accessory lateral system. Baudelot (1870, 15) 

 briefly mentions and figiu'es it (figs. 2 and 6) as the recurrent branch of the " trigeminus," 

 whilst Fee, who describes and figures in a number of Teleosts both the true lateral and 

 accessory lateral systems, agrees with the erroneous conclusion of Weber that both these 

 systems are perfectly homologous," although he had noticed that the true lateral nerve 

 was never connected with the spinal nerves. As the result of numerous experiments Fee 

 concluded that neither the triie nor the accessory lateral nerves were motor in function. 

 Owen (1866, 149) says (p. 303): — " A branch of the vagus ascends forward to join the 

 fifth in forming the dorsal division of the ' nervus lateralis,' which escapes by a foramen 

 in the parietal bone," by which it will be seen that both the anterior and posterior roots 

 of the accessory lateral were well known at that date. Baudelot (1868, 11) takes a 

 somewhat bold step when he compares a recurrent branch of the pathetic nerve 

 distributed to the pia mater with the ramus lateralis trigemini ! In the same volume 

 (12), after an investigation of Leuciscus riUilus, he concludes that the true and accessory 

 lateral nerves are perfectly homologous, and after referring to several authors who had 



* As 1 have been working from the second edition of Swan's Atlas, published in 18G4, I am taking it after 

 Stannius's work. The first edition, however, was published before Stannius's, and anticipated it in many important 

 respects, especially as regards the branches to the fins and the connections with the spinal nerves. 



