1892.] SPECIES OF EARTHWORMS. 691 



inary Notice of Earthworms from the Nilgiris and Shevaroys." 

 P. Z. S. 1886, p. 670. 



(7) R. HoRST. — "Descriptions of Earthworms. — I. Moniligaster 

 houtenii, n. sp., a gigantic Earthworm from Sumatra," Notes 

 Leyd. Mus. vol. ix. p. 97. 



(8) E. Perkier. — " Recherches pour servir a I'histoire des Lombri- 

 ciens terrestres." Nouv. Arch. Mus. vol. viii. p. 130. 



(9) D. Rosa. — " Viaggio di Leonardo Fea in Birmania e Regioni 



vicine : xxv. Moniligastridi, Geoscolecidi ed Eudrilidi." Ann. 

 Mus. Civ. Genova, ser. 2 a, vol. ix. p. 368. 



(10) W. MicHAELSEN. — " Terricoleu der Berliner Zoologischen 

 Sammlung." Arch. f. Nat. 1892, p. 209. 



In this list, it should be mentioned, I have only included 

 papers containing new facts with reference to the genus ; other 

 papers which refer to it will be quoted in their place in the course 

 of the following pages. 



External Characters. 



In the present species, which I name Moniligaster bahamensis, 

 the clitellum was fortunately developed ; it was not, however, visible 

 until the worm was examined by means of sections, and was then 

 found to occupy four segments, viz. x.-xiii. It will be remem- 

 bered that Perrier created a special group, the Aclitelliens, for 

 Moniligaster, since it appeared to possess no clitellum ; the anterior 

 segments were, however, described as resembling in certain particu- 

 lars the clitellum of other worms and as probably representing that 

 organ ; but it is not necessary to remark that frequently the anterior 

 segments of Earthworms, especially of the smaller species, are con- 

 siderably thicker, and also appear more opaque owing to the 

 enclosed viscera. The first to describe the clitellum was Prof. 

 Bourne ; he wrote that it occupied segments x.-xiii. ; but there 

 are no details given as to whether the clitellum was visible without 

 first having recourse to section-cutting ; it certainly is not in the 

 present species. The clitellum begins and ends sharp at the margins 

 of the segments wliich it occupies. The resemblance which the 

 forward position of the clitellum in Moniligaster gives this genus 

 to the Lumbriculidse need not be again emphasized ; I have already 

 sufficiently dwelt upon the matter. 



I have, however, now to refer to an interesting point with regard 

 to the clitellum which has not yet been described : the minute 

 structure of the clitellum differs from that of all other Earthworms 

 and agrees with that of ail " Water-worms " in being composed 

 of a single layer of cells only. This appears to me to be a point 

 of great importance ; coupled with the position of the clitellum it 

 gets even greater importance than it would otherwise have. Rosa 

 has sought to minimize the significance of the anterior position of 

 the clitellum ; but I do not think that anyone will deny that the 

 resemblance in structure which it shows to the lower Ohgochseta 

 cannot be explained away ; there is, moreover, no resemblance in 



