58 



In the region of the caudal zone the intestinal canal shows a pe- 

 cularity, first pointed out by Perrier, but as I believe overlooked by 

 Beddard, viz. the termination of the lamellar typhlosolis on this spot. 

 As above referred to, Perbier thinks the dilatation of the body 

 to be only due to this pecularity and I quite agree with him, that 

 this region of the intestinal canal is always bulged by alimentary 

 substance, in variance with Beddard, who found the intestine here 

 empty of debris. 



On examining the alimentary tract of Urochaeta, I observed 

 another peculiarity, singularly, not noted neither by Perrier nor 

 by Beddard, viz. that it is spirally coiled; this spiral begins 

 almost behind the clitellum and continues till the caudal extremity. 

 Each coil of the spiral corresponds to four segments, so that in 

 the anterior portion of the body, where the segments have a greater 

 longitudinal diameter than farther backwards , the coils are also longer 

 than in the posterior body-region. The intestine appears not to be 

 coiled in a true spiral, but to move rather backward in a com- 

 pressed zigzag line; for the dorsal vessel and the typhlosolis, which 

 are connected with the dorsal median line of the intestine, remain 

 in this situation. If it were a true spiral, the dorsal vessel and ty 

 phlosolis in one half of the coils ought to be situated ventrally . Schmarda 

 in his diagnosis of Pontoscolex also says : „der darm der einzige species ist 

 schraubenförmig gewunden, mit ausnähme des oberen theiles." This con- 

 firms Beddard's suggestion about the identity of this genus with Urochaeta. 



A spiral condition of the alimentary canal is described in Didymo- 

 gaster by Fletcher *) and in Plagiochaeta by Benham 2 ) ; Benham 

 states, that in the latter worm it is a true spiral. I have however 

 some doubt as to the exactness of this assertion, because the dorsal 

 vessel, which from its origin is connected with the dorsal median 

 line ot the intestine, appears to retain that position ; unfortunately the 

 typhlosolis is absent in this species. 



Perichaetidae. 



Within the last years a considerable number of species are referred 

 to the genus Perichaeta, which, though agreeing rather well with 



1) Proc. Linn. Society of N. S. Wales, 2e S. Vol. I, 1886, p. 554, PI. XI, fig. 8. 



2) Quartl. Journ. of Microsc. Science, Vol. XXXIII, 1892, p. 294, pi. XV. fig. 21. 





