684 OLIGOCHAETA 



possibly the glandular cells of the processes may also serve to form the cocoon, should 

 such exist — which is not yet known. In any case it is remarkable that in fully 

 adult specimens there should not be the least trace of a clitellum. The genus is 

 further characterized by the entire absence of gizzard and calciferous glands. 

 Four species of Siphonogaster have been described ; these are : — 



(i) S. aegyptiacns, Levinsen, Nile, 



(a) S. millsoni, Beddaed, Lagos. 



(3) S. emini, Michaelsbn, Victoria Nyanza. 



(4) S. stuhlmanni, MiCHAELSEN, Victoria Nyanza. 



The distribution area of these might lead to the inference that they were separate, 

 particularly in the case of ;Si. iniUsoni, for there is not, at present, a single instance 

 of the same species occurring on both sides of the African continent. 



The two last-mentioned species are principally to be distinguished by the form 

 of the genital seta, which in S. stuhlmanni have not the spatula-like outline that 

 they have in S. emini and the other two species ; there were also only a single pair 

 of them. The distinctness of S. emini and S. aegyptiacus is not so certain. 

 MiCHAELSEN defines it chiefly by the absence of the penes and their replacement 

 by 'dicke, hohe, wulstformige Hervorragungen.' It is suggested too that a median 

 ventral line between these processes bears the spermiducal pore. If the last suggestion 

 proves true the distinctness of the species (from S. millsoni, at any rate) is clear. 

 But it has certainly to be proved. I am not disposed to allow that there is necessarily 

 any difference in the penial processes ; in immature individuals of S. aegyptiacus from 

 the Nile mud I have found the processes in question very much in the same condition 

 as they are figured by Michaelsen ; so too* in the case of immature specimens of 

 S. Tnillsoni. With regard to these two species it is very difficult in the present state 

 of our knowledge of >Si. aegyptiacus to separate them. The only difference seems to 

 be that in S. aegyptiacus the penial setae are irregularly arranged upon the penes, 

 whereas in S. Tnillsoni they form two approximately regular series. 



(1) Siphonogaster aegyptiacus, Levinsen. 



S. aegyptiacus, Levinsen, Vid. Med., 1889, p. 319. 

 ?S. Emini, Michaelsen, JB. Hamb. wiss. Anst. ix, a, 189a, p. 8. 



Definition. Length, about 130 mm.; diameter, ^-4 mm. ; number of segments, \^q. Setae 

 not ornamented {Vj. Penial setae arranged irregularly on the penial processes. Hab. — 

 Nile; Bukoha, Victoria Nyanza. 



