242 Proceedings of the Royal Physical Society. 



The position that I myself take up in this particular 

 matter is one intermediate between that of the two natural- 

 ists. I do not consider it possible to retain a group Terri- 

 coloe. I consider that earthworms fall into two groups — 

 (1.) Lumbrici ; (2.) Moniligastres — each of which is equivalent 

 to any one of the various divisions, such as those enumerated 

 above, into which the aquatic Oligochseta fall. I do not, 

 however, for the present attempt to define what these groups 

 are. 



I define the two groups of Lumbrici and Moniligastres as 

 follows, my definition of Lumbrici being practically that 

 which Eosa applies to the Terricolae : — 



OLIGOCH^TA. 



Braxch a. Lumbrici. 



(1.) Two pairs of testes in segments x. and xi. ;^ sometimes 

 one is wanting, 



(2.) One to four pairs of sperm sacs, subdivided into num.e- 

 rous chambers, variously interconnected, sometimes 

 involving the testes and vas deferens funnels. 



(3.) Vasa defer entia opening into the segments which contain 

 the testes ; generally two {if one pair of testes, then one) 

 on each side, free until their termination or partially 

 fused. 



(4.) One pair j)f ovaries, generally in segment xiii.^ 



^ Rosa calls attention to the anomaly in the position of the testes, etc., in 

 Microchoeta, as recorded by Benham (Studies on Earthworms, No. 1 — Q. J. M. S., 

 vol, xxvi,, p. 278 et seq.). On examining a specimen of this worm (much 

 softened by imperfect preservation) it appeared to me that the funnels of the 

 vasa deferentia were in segments x. and xi. respectively, and not in ix. and x. ; 

 and that my original description (On the Anatomy and Systematic Position 

 of a Gigantic Earthworm, etc. — Trans. Zool. Soc, vol. xii., pt. 3) was so far 

 correct. On the other hand, I have satisfied myself that the vasa deferentia 

 open on to the exterior in segment xix., as Benham stated, and not on segment 

 xviii., as I stated. Probably, therefore, though I can make no positive 

 statement, the testes are also in x. and xi. 



Kosa fixes the position of the testes "contro alia parete anteriore" as 

 distinctive. I have, however, shown that in Acanthodrihis annectens they 

 are attached to hind wall of segment {see On the Anatomy of Three New 

 Species of Earthworms, etc. — Q. J. M. S., vol. xxx.). 



'^ One or two exceptions to this statement have been recorded. In Plutellus 

 (Peur'.er, fitude sur un genre nouveau des Lombriciens {Plutellus, E. P.)— 



