MEGASCOLECIDAE 287 



species of Dichogaster appear to be closely related to D. bolaiii, viz. D. malayana (Horst)^ 

 and D. rtigosa (Eisen) ; the former is primarily distinguished by the ring-shaped clitellum, 

 and the latter by its pigmentation. The specimens under consideration differ from typical 

 D. bolaui as follows : 



(i) Greater size; in this character they a^^roach. palmicola of Eisen, but differ from 

 specimens referred to this variety by Stephenson-, which are quite small. 



(2) Pigmentation of one specimen (the others may be either faded or really not 

 pigmented). In this character there is an approach to D. rugosa. Michaelsen^ makes the 

 following statement concerning certain specimens of D. bolaui from New Caledonia 

 " Die Stiicke von der Station am Fluss bei Cone sind mit einer Farben-Angabe iiber die 

 lebenden Tiere versehen: Vorder-Ende 'rosarot'". Stephenson* also describes var. 

 malabarica as with a dark mid-dorsal stripe. It would therefore seem that a trace of 

 pigmentation is of doubtful taxonomic significance in this species, and in the absence of 

 other very definite distinguishing characters it is doubtful whether D. rugosa should be 

 retained as a distinct species (the form of the distal end of the smooth penial setae {} b) 

 is probably not sufficiently different to be treated as a specific character). 



(3) Nephridia in four rows on each side. In this character the present specimens agree 

 with octonephra and also with D. rugosa. In decanephra there are five rows while in the 

 other forms under consideration there are only three. 



(4) Two pairs of seminal vesicles in segments 11 and 12. The additional pair of 

 seminal vesicles also characterizes octouephra, palmicola and pacifica. 



(5) Gizzards in segments 6 and 7 instead of 7 and 8. Stephenson^ records this peculi- 

 arity for specimens of otherwise typical D. bolaui from Burma. The absence of septum 

 6/7 is paralleled by the absence of septum 7/8 in palmicola and pacifica. 



(6) The distal end of penial seta b (the smooth seta) is not broadened or spoon- 

 shaped, but merely flattened and slightly notched. Michaelsen'' has described a similar 

 reduction of the distal end for decanephra from the island of Annobon. Although the 

 present specimens differ from decanephra in their larger size and in the number of 

 nephridial rows it is significant that the form of the penial setae should be similar, since 

 they come from the same locality. 



On the whole the present specimens agree most closely with octonephra, but from this 

 variety they differ in the indications of pigmentation, in their larger size and in the form 

 of the distal end of penial seta b. D. bolaui appears to be a very variable species and it is 

 doubtful how far the different forms described are really taxonomically significant. 



1 Stephenson {Rec. Ind. Mus., .xxxni, p. 195) considers D. bolaui and D. malayana to be identical. 



^ Stephenson, J., Rec. Ind. Mus., xii, p. 348. 



^ Michaelsen, W., in : Sarasin, F., and Roux, J., Nova Caledonia, Zoologie, i, p. 273. Wiesbaden. 



^ Stephenson, J., Mem. Ind. Mus., vii, p. 257. 



^ Ibid., Proc. Zool. Soc. London, 1931, i, p. 65. 



* Michaelsen, W., Ergeb. d. Zweiten Deutsch. Zentral-Afrika-Exped. 1910-11, i, Zoologie, p. 191. Leipzig. 



