No. I.] THE CRANIAL NERVES OF AMPHIBIA. 185 



VIII, while in the latter it is just ventral to the VIII. This 

 change is perhaps correlated with the change in position of the 

 Auditory, which has already been touched upon. 



It may be most conveniently noted here that Burckhardt (11) 

 describes in Protopterus a dorsal root belonging to the VII, 

 partly motor, a root beneath it from the fasciculus communis, 

 which he attributes to the VIII {^^ Villi') in his nomenclature, 

 a second and largest root to the VIII {^^ VIII 2') below this, 

 then finally and most ventral a root derived partly from the 

 posterior longitudinal fasciculus and partly from a motor 

 nucleus. This latter he also attributes to the VIII (*' VIII t,. 4"). 

 Burckhardt probably follows O shorn in this assignment of 

 these roots, which are so very similar to those in Crypto- 

 branchus. In this, as we have seen already, he is mistaken. 

 The dorsal root is the lateral line root, and is entirely sensory. 

 The fasciculus communis root and the most ventral root should 

 be assigned to the VII and not to the VIII. The VIII is 

 represented entirely by the largest root {''VIII 2') between 

 the two last mentioned. 



The most interesting fact to be noticed here is that in the 

 position of its fasciculus communis root, Protopterus agrees 

 with the Urodela and differs from the tadpole, from Anura, 

 from Acipenser, and not improbably, if the views taken on 

 p. 193 be proved correct, from Selachii in this respect. 



{b) Higher Vertebrates. — Before looking further at the 

 lower vertebrates it may be well to take a glance at the higher 

 forms. In the human medulla, as is well known, the prin- 

 cipal sources of the IX + X are three, (i) from a motor 

 nucleus, the nucleus ambiguus, (2) from a so-called sensory 

 nucleus, and (3) from the fasciculus solitarius. We have also 

 the motor nuclei of the XI, principally similar or identical with 

 those of the IX + X. 



Kolliker, in the latest edition of his Gewebelehre^ gives a 

 very clear and complete account of the fasciculus solitarius. 

 It is apparent some distance caudad of the calamus scriptorius 

 lying latero-dorsad of the sensory terminal nucleus of the 

 IX + X, and consequently quite near the median line in the 

 dorsal part of the cord. It gradually increases in size as it 



