174 MR. F. J. COLE ON THE STEUCTURE AND MORPHOLOGY OF 



The most complete account of the system to lie found in modern literature is that 

 published in the admirable work on the vagus group of Teleosts by B. Haller in the 

 third volume of the " Festschrift fiir Gegenbaur " (1897, 97). Haller carefully redescribes 

 the origin of Weber's accessorius (= accessory lateral in part) in Cj/priiuis carpi 0, where 

 the accessorius is found in a very interesting, and perhaps primitive, condition. An 

 anterior root (Taf. ii. figs. 7 & 8 a) is formed by the union of two twigs from the 

 Gasserian ganglion, one from each side, and two twigs from the facial ganglion. This 

 root passes l)ackwards and anastomoses with the fused " ventral roots of the vagus " 

 (Gegenbaur), or what is usvially identified as the Ichthyopsid " hypoglossal.'" Erom the 

 ganglion of the latter close to the entry of the root above, arises one of the roots of the 

 accessory lateral system, which passes upwards, receives a root from the vagus, and then 

 doubtless has the usual peripheral distribution. Before a correct interpretation of these 

 roots and nerves is possible, an investigation will hiive to be conducted as to the internal 

 origin and peripheral distribution of the fibres of the roots above described, and this has 

 yet to be done. My own provisional interpretation differs from that given by Haller, 

 and is perhaps the more logical one in the present state of our knowledge. We know 

 that a generalised accessory lateral system would consist of the collected dorsal somatic 

 sensory branches, or portions of them, of the Vth, Vllth, IXth, and Xth cranial nerves, 

 and most of the spinal nerves. Haller's nerve a, therefore, form^ what is doubtless the 

 morphological anterior root of the accessory lateral system. It is anomalous in so far as, 

 instead of anastomosing directly with the posterior or vagal root, it passes first backwards 

 to the hypoglossal ganglion. The dorsal branch that leaves the hypoglossal ganglion, 

 therefore, represents the morphological posterior extremity of the anterior or trigemino- 

 facial root (Haller's nerve a) of the accessory lateral system, +t^oubtless the additional 

 dorsal branch of the hypoglossal. The posterior or vagal root is normal. The peculiarity 

 of the accessory lateral system in Cyprinus, therefore, is that the anterior root first 

 " collects " the dorsal branch of the hypoglossal, instead of that branch being collected 

 after the two roots of the system have united and the resulting trunk is passing 

 backwards. This irregularity has necessarily resulted in the morphological anterior 

 root as it passes upwards occupying a j)osition posterior to the posterior root. Should 

 my interpretation of these nerves prove on further investigation to be correct, Cyprlnns 

 \\\\\ have provided us with a very interesting and unique cliaptcr in the history of the 

 accessory lateral nerves. 



C. J. Herrick *, in a recent note (1S97, 98), describes the accessory lateral nerve of 

 Meiiidia notata as folloAvs (p. 428) : — " Ramus recurrens VII. Commonly called ramus 

 recurrens V, but as the fibres are all fasciculus communis, that name is inappropriate. 

 These fibres arise from the geniculate ganglion in several strands, pass dorsad in the 

 meninges and finally emerge on the dorsal surface of the head, and then turn caudad 

 into the trunk. They anastomose with each other, and farther back with the dorsal ramus 

 of each spinal nerve. I have not been able to demonstrate that they supply either 



* This author, bj the way, accuses me in my Ckhmrra paper of associating the lateral lino system with the facial 

 nerve. He must surely have overlooked paragraph 5 on p. 638, in which I point ont that such an association must 

 be considered as purely provisional and not morphological. 



