597 



ventral lateral liue root, which latter was itself placed too far down 

 on the medulla (cp, present figure with op. cit., PI. 2, Fig. 3). 

 Strong ^) has already drawn attention to this anomaly and we are 

 now able to clear up the point. The so-called ventral lateral line root 

 is not a ventral but a lateral root, and the auditory nerve arises from 

 the medulla immediately behind the ventral half of it. Its correct 

 position is indicated in the figure we now give. It is in fact so closely 

 attached to the lateral line root that when this is carefully removed 

 the auditory nerve comes away with it. 



Perhaps the most important point in the cranial nerves of Chi- 

 maera is the complete and unique independence at the very outset of 

 the lateral line nerves. Here these nerves form a discrete system 

 which cannot be definitely associated with any other cranial nerve, 

 and is a striking instance of the importance of the doctrine of the 

 nerve components. This was first described in the former paper, and we 

 are now able to confirm what was there stated and to add some further 

 interesting details. 



Following the traditional practice of associating all the lateral 

 line nerves except the lateralis with the facial, the latter nerve may 

 be epitomized as follows : There are three large nerve trunks — 1 the 

 ophthalmic (lateral line); 2 the buccal (lateral line); and VII + 3 

 the hyomandibular trunk {= facial sensu stricto + external mandi- 

 bular or lateral line component). These three nerves arise by three 

 roots — a a very large dorsal root arising high up immediately 

 behind the restiform body from a special lobe of the medulla forming per- 

 haps the lobus lineae lateralis (dorsal lateral line root); h a very 

 large root arising at the same transverse level as the first but from 

 the ventro-lateral surface of the medulla (lateral lateral line root) ; and 

 c a smaller root also arising at the same transverse level but from 

 the ventral surface of the medulla (root of the facial sensu stricto). 



Now each of the three lateral line nerves (ophthalmic, buccal and 

 external mandibular) contributes fibres to both the dorsal and lateral 

 roots, and each may therefore be described as arising by a dorsal and 

 a lateral rootlet. In the case of the ophthalmic nerve this was already 

 known from the previous memoir, but the splitting was not recognised 

 in the other two roots. 



The Hyomandibular Trunk. — This is easily resolvable 

 microscopically into two parts — 1) the external mandibular nerve 

 or lateral line component (5) and 2) the facialis sensu stricto {VIT). 

 The former is given ofif from the trunk in front to accompany the 



1) Journ. Comp. Neurol., Vol. 8, 1898, p. Y. 



