Manchester Memoirs, Vol. I. (1905), No. 1. 



I. Note on the Buccal Pits of Peripatus. 

 By C. Gordon Hewitt, B.Sc, 



Demonstrator of Zoology in the University of Manchester. 



(Communicated by Professor S. J. Hickson, F.R.S.). 

 Received and Read, October jrd, igoj. 



The earliest detailed account of these structures* is 

 that given in a memoir on Peripatus capensis by Balfour ( i ), 

 who, after describing the characters of the outer and 

 inner pairs of jaws, adds (p. 222) — " A more important 

 difference between the two blades than in the character of 

 the cutting edge just spoken of, is to be found in their 

 relation to the muscles which move them. The anterior 

 parts of both blades are placed on two epithelial ridges, 

 which are moved by muscles common to both blades 

 (//. yiv\.,Jig. 11). Posteriorly, however, the behaviour of 

 the two blades is very different. The epithelial ridge 

 bearing the outer blade is continued back for a short 

 distance behind the blade, but the cuticle covering it 

 becomes very thin, and it forms a simple epithelial ridge 

 placed parallel to the inner blade. The cuticle covering 

 the epithelial ridge of the inner blade is, on the contrary, 

 prolonged behind the blade itself as a thick rod, which, 

 penetrating backwards along a deep pocket of the buccal 

 epithelium, behind the main part of the buccal cavity for 

 the whole length of the pharynx, forms a very powerful 



* In Moseley's account (2) of this species the following words may refer 

 to these structures: " From the posterior part of the lateral surfaces of the 

 pharynx, a pair of small muscles which probably are protractors of the 

 pharynx, and serve to push forward the jaws," 



October 21st, igo^. 



