184 ME. F. J. COLE ON THE STRUCTURE AND MORPHOLOGY OF 



mandibular, and the otic nerve innervates the free anterior extremity of the lateralis 

 canal, which extremity must therefore be considered to belong to the infra-orbital line. 

 In the Skate {Mala hatis) the remarkable reduction of the dermal tubules in several 

 places is a noteworthy feature, and enjoins an investigation into the development of these 

 portions of the canal system (Ewart & Mitchell, 1802, 69). 



Pollard (1892, 161) states that the superficial ojihthalmic and buccal lateral line 

 nerves arise from a single trunk in Clarias (p. 529) and Auclieiiaspls (p. 532). This 

 is interesting when we remember the description of the development of these canals 

 given by Wilson, Mitrophanow, and Locy. In Callicthys, however, the otic nerve arises 

 separately from the ganglionic complex and not from the buccal nerve (j)p. 534-535). 

 In Clarias sense organ 1 of the lateralis canal [-— s. 0. 7 main canal, Pollard) is stated 

 in the text (p. 529) to be suj)plied by the glossopharyngeal, whilst the figure of this form 

 shows an innervation from the lateralis lateral line nerve. On p. 534 in Callicthys 

 the ampullation of the " main canal " is described as a " remarkable phenomenon, 

 hitherto unrecorded in any other animal." It is in fact described by several authors, 

 notably by Traquair (18G5, 207), Hyrtl (186G, 105), and Sappey (1880, 175). In Clarias, 

 Auchenaspis, and Choitostomns tb(> operculo-mandibular canal communicates with the 

 body-canal, but in the Siluroids, where the canal system is reduced, it is unconnected 

 with any of the other canals. In comparing the lateral line system of Siluroids with 

 Coccoslens, Pollard apparently overlooked until too late the accurate description by 

 Traquair published two years before, and makes use of the somewhat erroneous figure 

 by Pander. 



The lateralis lateral line nerve of Ferca, according to Cuvier and Valenciennes (1830, 



57;, Vogt and Yung (1894, 215), and other authors, is in much the same condition as in 



Gadus, dividing into an upper ramus to the anterior portion of the body canal, and a 



lower ramus to the posterior portion of the same canal*. Herrick (1897, 98) finds in 



the highly specialised Acanthopteran Meuidia that although macroscopically the nerves 



are fused and their relations disguised, yet microscopically the whole of them may be 



reduced to the common tyj)e, of which Lmmargus, Raia, Chimcera, Protopterus, Amia, 



Gadus, and the Siluroids are other examples. The vagus ganglion can be broken up 



into five ganglia — four of which belong to the branchial nerves and one to the visceralis. 



Herrick finds the body canal of Menidia occupying a superficial position posteriorly just 



as it does in Gadus, and further points out that the lateral line branch of the glosso- 



pharyngeus is really a branch of the laterahs. The common origin of the lateral line 



and avxditory nerves is confirmed, and the V-VIIth nerves arise by a double root as in 



Gadus, of which the ventral one is the motor root of the facial and is connected with 



the hyomandibular trunk only. All the lateral Line nerves, except the lateralis, arise 



from the dorsal root of the trigemino-facial complex, but in two handles — a dorsal 



bvmdle for the superficial ophthaluuc + l^^i^ccal, and a ventral l)undle for the external 



maudibidar. The otic nerve innervates three sense organs, whilst two aj^parently derive 



* In ri-otoji>tt:rvii thfic are four rami to the lateralis, and nil (lislliiciivih/ laUrcil line nerves (I'inkus, 1894, 157), 

 whilst the aceessorv lateral system is eompletely absent. 



