1888.] MR. BEDDARD ON THE STRUCTURE OF CLITELLIO. 485 



2. On certain Points in the Structure of Clitellio (Claparede) . 

 By Frank E. Beddard, M.A.^ Prosector to the Society '. 



[Received September 5, 1888.] 

 (Plate XXIII.) 



The sandy mud upon the shores of the Sound at Plymouth was 

 invariably found to contain large numbers of a small slender 

 Oiio;ocbete of a dark greenish-grey colour. The worm ap[)ears to 

 be identical with Claparcde's Clitellio ater ' ; the same mud also very 

 frequently contained examples of another species of Clitellio, which 

 is jjrobably C. arenarius ^. The obvious difference between these two 

 species was the absence, in the latter, of the peculiar dark papillae 

 which cover the surface of the body in C. ater, and which appear 

 to be characteristic of that species. I never found these worms in 

 any other situation, and they were invariably absent from the coarser 

 sands, which were exclusively occupied (as regards Oligochseta) by 

 certain species of Pachydrilus, upon which I hope to offL-r some 

 notes to the Society later. 



Although Claparede has given a tolerably full account of the 

 structure of Clitellio, especially of Clitellio arenarius, t am able to 

 add some few facts to our knowledge of the worm ; my remarks 

 partly deal with C. ater, and partly with the transparent species 

 which I shall call C. arenarius^, 



Clitellio ater is, as Claparede remarks, characterized by the dark 

 colour of the integument, which, however, is not developed ffig. A, 

 p. 48(j) upon the anterior extremity of the body, upon the last few 

 segments, and upon the clitellum. The colour is due to innumerable 

 papillae the shape and structure of which do not appear to me to be 

 well illustrated in Claparede's drawing"; on the other hand, the general 

 appearance of the body due to these peculiar structures is very well 

 shown in Claparede's figure ^ They are somewhat leaf-shaped with 

 a pointed apex, the base being attached to the cuticle ; the interior 

 of each papilla is filled with greyish-green granules. 



Claparede's description of the setae is, so far as my observations 

 enable me to state, incorrect ; be states that the setae are arranged in 

 two double rows, and are alike in both rows, being bifid at the 

 extremity or terminating in a simple point. This character is, in fact, 



''■ From observations made at the Plymouth station of the Marine Biohigieal 

 Association. 



■^ Ed. Claparede, " Eecherches anatomiques sur les Oligochetes," Mem. Soc. 

 Phys. Geneve, t. xvi. j;i862), p. 253. 



■* Ed. Claparede, " Etudes an:itomiques sur les Annelides &c.," torn. cit. p. 102. 



* Several other species of Cliicllio have been described, for a list of which 

 see Vejdovsky's ' System u. Morph. d. Oligochaeten,' Prag, 1874, p. 4.5 ; the 

 majority of these have been described by Ozei-niavsky (Bull. Soc. Imp. Nat. 

 Moscou, t. Iv. pt. ii. (1880), p. .324, &c.). I am not able at present to determine 

 what are the points of difference between these species and C. arenarius. 



■' Eeoherches, &c., loc. cit. pi. iv. fig. 10. 



" Loc. cit. pi. iv. flg. y. 



