THE CRANIAL NERVES AND LATERAL SENSE ORGANS OF FISHES. 167 



writers, the point is of no importance, but may serve to emphasize the correctness of the 

 homology. 



The first description of the accessory lateral nerve is to be found in E. H. Weber's 

 famous work on the auditory organ of fishes (1820, 216). He here describes and figures 

 {i. e. root only, tab. v. fig. 30) the nerve afterwards called the " recurrent facial " of 

 Silurus glanis. He says : — " Ramus primus nervi trigemini, per tectum cranii exiens, 

 (in apicibus processuum spinosorum ad caudam usque progrediens, ibique cum nervis 

 spinalibus ramisque nervi lateralis magni plexum complicitum nervorum componens,) 

 nervi lateralis accessorii nomine appellandus." There can be no doubt as to the homoloo-v 

 of this nerve, and it is to be noted that Weber considered it a bi'anch of the trigeminus 

 and not of the facial as his successors did. 



Desmoulins & Magendie (1827, 60) refer to the nerve as the " pterigo-dorsal " 

 (Part II. p. 869), and were the first to recognise the homology between it and the 

 superficial nerve of tlie higher Teleosts. They give a fairly long description of its 

 peripheral distribution in the latter fishes, which is, however, not as accurate as that 

 published later by Stannius. Weber himself in 1827 (217J devotes further attention to 

 the matter, and successfully homologises his first nerve with the elaborate cutaneous 

 system in " Gadus lota " ( =Lota vtdgaris), thus confirming independently the conclusion 

 of Desmoulins & Magendie. He renames the system the " Ramus lateralis trigemini," 

 which is the name by which it has usually been known to anatomists, and describes its 

 anastomoses with the spinal nerves. 



In 1830, Cuvier & Valenciennes devote a section of their work on the Natural 

 History of Fishes (57) to a consideration of the accessory lateral nerves. They are 

 both figured and described (t. i. pp. 440-44'l), and erroneously considered to be 

 largely motor. The anterior and posterior roots are described, and so also are the 

 anastomoses of the dorsal ramus with the spinal nerves. They found the branches to 

 the pectoral and anal fins, but not, however, to the pelvic, and clearly recognised the 

 homology between the recurrent nerve of the Siluroids and the better develojied system 

 in the specialised Teleosts, believing that representatives of the system were probablv to 

 be found in all tishes. Their figure of the nerves of the Perch, showing the accessory 

 lateral nerves, has been copied by Owen (149, vol. i. p. 304), Nuhn (146, p. 558), and into 

 several other text-books. Biichner (1835, 36) states that the accessory lateral is 

 characteristically developed in the Cyprinoids, and describes it in " Ci/printis barbus " 

 {^zBarbus vulgaris), but fails to distmguish it from the lateralis lateral line nerve. He, 

 however, correctly compares it with its more specialised form in the modern 

 Teleosts. Alcock (1839, 3) says (p. 268) : " Lastly, in many [fishes] the nerve [trigeminus] 

 is distributed in a manner and to an extent for which there is no analogy among other 

 animals, the fins being throughout furnished with branches from the fifth. Hence in 

 fish, in which the distribution of the nerve is so much more extended than in other 

 animals, both the size of it is proportionately greater, and it consists of a greater number 

 of divisions ; these, which in the three other classes of vertebrate animals are only three, 

 amounting with them to from three to six." A figure of the brain and " fifth " nerve of 

 the Cod is given on p. 276, which shows the anterior root of the accessory lateral nerve 



