1891.] 



EARTHWORM FROM WEST AFRICA. 



49 



in length, with a diameter at the widest part of about ^ inch. As 

 the specimens were much softened, this length probably represents 

 the extreme length of the worm in its most extended condition. 

 The colour was almost black at the anterior end ; further back a 

 brown tint predominated ; the posterior end of the body showed in 

 many specimens a pecuUar dark green colour, something like that 

 of Microchceta rappii^. The appendages in question are as shown 

 in the accompanying drawings (woodcuts, figs. 1, 2), small, not longer 



Fig. 1. 



Siphonogaster millsoni. 

 Ventral riew of anterior segments, showing the processes of segment xviii. 



than two segments ; they are directed backwards and appear some- 

 times as if they were adherent along their whole length to the 

 ventral parietes. In other specimens they hang freely down. 



Levinsen is in some little doubt about the number of the segment 

 to which the appendages are attached. In S. millsoni they arise 

 without doubt from the eighteenth segment, close to each other and 

 on either side of the ventral middle line. 



Their origin is from the middle of the antero-posterior diameter 

 of the segment, just where the ventral pair of setse would be placed 

 were they developed upon this segment. They correspond, in fact, 

 exactly to the first seta, as may be seen by an inspection of the 

 ventral surface of the worm mounted in glycerine on a slide. 



The setce of this species, it should be remarked, are in couples, 

 the distance between the individual setse of each couple being con- 

 siderable — greater in the case of the ventral couple. 



^ Beddard, "On the Anatomy and Systematic Position of a Gigantic Earth- 

 worm, &c.," Trans. Zool. Soc. vol. xii. p. 63, pi. xir. 



Proc. Zool. Soc— 1891, No. IV. 4 



