58 ALFRED GIBBS BOURNE. 



The inner wall is much plicated, being raised into ridges 

 and papillsBj and is excessively vascular. 



The two most posteriorly placed glands are smaller than the 

 other four. 



It is beyond the scope of the present paper to discuss the 

 relation of these glands to those found in other worms. I 

 will merely remark that this is a very common type of calci- 

 ferous gland among the Perichsetidse, though by no means the 

 only one. It is^ moreover, the simplest. 



Beddard mentions no such glands in " Pleurochgeta." 



In segments xvi and xvii there is a further portion of the 

 narrow oesophagus, and in the latter of these this suddenly 

 widens out into the intestine. 



The intestine is, as Beddard has pointed out, for '' Pleuro- 

 chseta" very complicated. 



The anterior portion may be called the typhlosolar region, 

 and the posterior the post-typhlosolar region. 



The typhlosole is in a very rudimentary condition. It is a 

 mere ridge of the intestine projecting into the lumen along 

 the median dorsal line. As stated below (pp. 61 and 70), 

 there is no continuous longitudinal blood-vessel running along 

 it, but the capillary network becomes so exceedingly dense here 

 as to form a longitudinally placed blood lacuna. 



This typhlosole extends as far back as segment cxxxv. 



In the anterior portion of the typhlosolar region I find the 

 intestinal wall forming the pouches described by Beddard (1, 

 p. 492). In segments xvii to xxxv there are the large simple 

 pouches, and in segments xxxvi to xlii are the seven pairs of 

 sacculated pouches which correspond very closely to Beddard's 

 description. 



Posteriorly to these sacculated pouches the intestinal wall 

 is not protruded to any great extent into pouches. 



the Physiological Laboratory, University College, London, and am indebted 

 to him for the information that they undoubtedly consist almost entirely of 

 carbonate of lime. But he says, " A few shreds of organic matter remain 

 undissolved. When the concretions arc treated with acid, these prove to be 

 of proteid nature," 



