2 Hewitt, Note on the Buccal Pits of Peripatus. 



lever, on which a great part of the muscles connected 

 with the jaws find their insertion. The relations of the 

 epithelial pocket bearing this lever are somewhat peculiar. 



" The part of the epithelial ridge bearing the proximal 

 part of this lever is bounded on both its outer and inner 

 aspect by a deep groove. The wall of the outer groove is 

 formed by the epithelial ridge of the outer blade, and that 

 of the inner by a special epithelial ridge at the side of 

 the tongue. Close to the hinder border of the buccal 

 cavity (as shown in pi. x.v\.,fig. 12, on the right hand side) 

 the outer walls of these two grooves meet over the lever, 

 so as to completely enclose it in an epithelial tube, and 

 almost immediately behind this point the epithelial tube 

 is detached from the oral epithelium, and appears in 

 section as a tube with a chitinous rod in its interior, 

 lying freely in the body cavity (shown in pi xvi., figs. 

 13 — 16 le). This apparent tube is the section of the 

 deep pit already spoken of It may be traced back even 

 beyond the end of the pharynx, and serves along its 

 whole length for the attachment of muscles." 



I have not had the opportunity of examining sections 

 of these jaw -levers in P. cnpejisis, but have done so in 

 series of sections of P. balfouri, P. novae zeaiandiae and 

 Ooperipatus ovipanis (Dendy) and in every case the 

 chitinous rod was hollow and not solid as described and 

 figured by Balfour in the case of i^. cape?isis. The hollow 

 nature of these jaw levers has already been described by 

 Prof Dendy in his memoir on the oviparous species of 

 Peripatus (3). He assigns a respiratory function to these 

 hollow jaw-levers, which form the buccal pits, as will be 

 seen from the following description of them, which he 

 gives. Referring to O. oviparus, he says (p. 371): "In this 

 species (and probably in the others) there is a tracheal pit 

 immediately in front of the mouth, and a pair of very 



