4 OLOF LARSELL 



This nerve had previously been figured by Fritsch in the sela- 

 chian, Galeus, in 1878, and had been mentioned in 1893, by C. L. 

 Herrick in the urodele amphibian, Necturus. The observations 

 of Fritsch and Herrick, however, were merely incidental, in con- 

 nection with other work, and the significance of the observations 

 escaped them. 



After these anticipatory glimpses the nerve remained unno- 

 ticed until Pinkus described it in Protopterus in 1894. In 1895, 

 in a more extended paper, Pinkus figured and described it as ly- 

 ing ventral to the olfactory nerve and extending caudad over 

 the ventral surface of the forebrain to the recessus praeopticus, 

 its peripheral terminations being in the olfactory sac. Thus, 

 although first figured in selachians, it was first described with 

 sketches, in the Dipnoi. 



Shortly afterward, AUis ('97) described and figured in the 

 ganoid fish, Amia, a strand which he traced centrally to the 

 bulbus olfactorius and peripherally to the olfactory capsule. 

 He considered this strand to be homologous with the nerve de- 

 scribed by Pinkus. In his comments regarding the possible 

 function of the nerve, he suggested that it might be of sympathetic 

 type. This is interesting in view of the position taken by Brook- 

 over and others and of the demonstration of the presence of 

 sympathetic fibers in the bundle of the nervus terminalis of 

 mammals. 



Now appeared the first study of the embryological history of 

 the nerve (Locy, '99) together with a description of its adult 

 condition in Squalus acanthias. In this form the nerve was 

 described and figured as possessing a compact ganglion, as con- 

 nected with the brain in the fissure between the lobes of the tel- 

 encephalon, and as distributed anteriorly to the lateral part of 

 the olfactory capsule and entering between the folds of the nasal 

 epithelium. It was claimed that the nerve arises from the neu- 

 ral crest before the appearance of the olfactory fibers. At that 

 time Locy considered as doubtful its homology with the nerve 

 described by Pinkus, and provisionally designated it as a median 

 'accessory olfactory strand.' In 1903, after observing the same 

 nerve in six genera of selachians, Locy reversed his earlier opin- 



