THE PERIPHERAL DISTRIBUTION OF THE CRANIAL 

 NERVES OF NECTURUS MACULATUS. 



BY H. W. NORRIS AND MARGARET BUCKLEY. 



Although Nectums is so commonly used in laboratory courses of 

 vertebrate dissection there have been few attempts made to give a sys- 

 tematic account of its cranial nerves. Laboratory guides and outlines 

 still adhere to an antiquated nomenclature in reference to the nervous 

 system of Necturus, for which procedure there is little excuse in the 

 light of the work that has been done already on the nervous systems of 

 other Urodela. 



The oldest account we have of the cranial nerves of Necturus seems 

 to be that of Fischer (1864). From the figures which he gives it is 

 evident that there has been little added to our knowledge of the gen- 

 eral topography of the fifth, seventh, ninth and tenth nerves since his 

 contributions were made. The origins of the cranial nerves were de- 

 scribed with great care and accuracy by Kingsbury (1895) in his paper 

 on the brain of Necturus. Druner (1902) has given a very thorough 

 description of the seventh, ninth, tenth and hypoglossal nerves in their 

 relation to the branchial arches and the connected musculature. The 

 development of the peripheral nervous system in Necturus, particu- 

 larly of the lateral line system, has been made known through the ob- 

 servations of ]Miss Piatt (1896). To the present time there has ap- 

 peared no systematic account of the nerve components in Necturus. 

 To supply this information this paper is a preliminary attempt. 



The descriptions in this paper are based largely upon studies made 

 with serial sections of larvae of 35 mm. in length. The material was 

 fixed in vom Rath's pico-aceto-platino-osmic mixture, and sectioned in 

 the three conventional planes. Plottings of the cranial and first and 

 second spinal nerves were made upon the sagittal plane, enlarged about 

 250 times. 



In general it may be said that the cranial nerves of Necturus do not 

 indicate a primitive or ancestral condition. Rather they conform very 

 closely to the arrangement in the Salamandridae as it has been de- 

 scrilicd in Amblj^stoma (Coghill, 1902) and Spelerpes (Bowers, 1900). 



