216 W. B. BENHAM. 



couple of somites ; but in those cases where the gizzard is 

 far forwards there is a greater extent of intestine in which 

 the typhlosole is absent, and in which the walls are not 

 distinctly sacculated or nipped by the septa. This non- 

 typhlosolar region is the "tubular intestine;" and on it, 

 instead of in the oesophagus, are situated the calciferous or 

 other diverticula of the gut in genera with an anteriorly 

 situated gizzard. 



The typhlosolar region appears to begin, in the majority of 

 cases, somewhere about Somites xiv to xvi ; but we have very 

 scanty material for generalising on this point. Many of the 

 diagrams of the canal are correct only so far as the position of 

 the calciferous glands go. In the majority of cases authors 

 confine themselves to the position of gizzard and glands, and 

 rarely state where the typhlosolar or sacculated region com- 

 mences. 



Only a few cases is this typhlosole absent, e.g. Ponto- 

 drilus, Microscolex. It is sometimes a mere thin, com- 

 pressed fold ; or it is cylindrical, and nearly fills the cavity of 

 the intestine. Rhinodrilus is peculiar — at any rate, no record 

 of this has been published — in having its typhlosole, which is 

 a mere fold, attached along a spiral line running round the 

 intestine, instead of hanging down from the dorsal mid-line. 



In a few cases — Perichseta, Urobenus, Hormogaster- — 

 the hinder part of the "tubular" region is distinctly pouched; 

 not merely nipped by the successive septa, but with thick 

 walls, giving rise to a number of paired pouches, the walls of 

 which are probably more vascular than elsewhere. This 

 thrusts the commencement of the sacculated or typhlosolar 

 region backwards ; and the point of union is marked by a pair 

 (rarely more pairs in some sp. Perichseta) of blind cylindrical 

 outgrowths or " intestinal ca3ca.^^ These lie in Somite xxi in 

 Hormogaster, in Somite xxvi in Perichaita and Uro- 

 benus. I may mention once more that some worms, referred 

 to Pericha^ta, are deprived of these ceeca; and I believe this 

 negative character goes band in hand with a forward position 

 of the gizzard. 



