398 



the condition of his material allowed him to speak with any certainly. 

 It is unnecessary therefore to give an account of the general form 

 of the labyrinth or of the relative positions of the recessus utriculi 

 and sacculus or of the passages by which they are connected 

 together and to the utricle (figs. 1 — 3). 



With regard to the nerves that supply the several maculge and 

 the cristre of the semicircular canals I find that in Colonel Shepherd's 

 specimen the two main trunks — the ramus anterior and the ramus 

 posterior — (fig. 1, 2, 3, EA. EP.) are more independent and clearly 

 separated from one another than one would be led to infer from 

 Eetzius's figures (PI. 24, fig. 1—4). 



Their distribution also overlaps in a way that apparently was not 

 so in his specimen. The ramus anterior supplies the cristas of the 



anterior and external semicir- 

 cular canals and the macula of 

 the recessus utriculi in the usual 

 way but it also sends a branch 

 of considerable size (fig. 1, E.Ö.) 

 into the territory of the post- 

 erior branch to the anterior and 

 upper end of the macula of the 

 sacculus as figured by Eetzius 

 in Protopterus (PI. 24, fig. 9). 

 This is a condition not at all 

 unusual in sharks and is for 

 instance figured by Professor 

 Stewart^) in Carcharias. 



In this specimen too I was 

 unable to distinguish a macula 

 lagenie separated from the com- 

 mon macula of the saccule. 

 Owing to the imperfect preservation of his material Eetzius 

 was unable to state whether the macula neglecta — a small nerve 

 ending situated upon the lower surface of the utricle in close proxi- 

 mity to the hinder limit of the utriculo-sacculine passage — was 

 present or not; though as he had seen it in Protopterus he asserted 



R A- 



RS - 



Fig. 2. The left labyrinth of Neocera- 

 todus forsteri. seen from in front, with part 

 of the wall of the Sacculus, ductus endo- 

 lymphaticus and recessus utriculi removed. 

 Reference letters as in Fig. 1- 



1) Stewart, Membranous labyrinths of certain Sharks, Jour. Linn. Soc. 

 Vol. 29, 1906, pi. 40, fig. 5. 



