1901.] OF THE OEXrs lU.XHAMIA. 199 



pores are surrounded by a small pale area and the clitelluui is 

 yellowish. 



The prostomium is larger than that of B. moorei ; ir is retracted 

 within the buccal cavity, and is divided off from the buccal 

 segment by a complete groove which dips faintly into the segment. 

 The arrangement of the prostomium is that denominated i- pro- 

 epilobisch " by Dr. Michaelsen. It is convenient to have terms 

 for the varying condition of the prostomium which is so frequently 

 of use in the discrimination of species or genera, as in the present 

 instance. But it would be as well perhaps to convert Michaelsen's 

 terms into more purely Greek compounds. I would suggest that 

 the terms should be epicheilous. J:c. The dorsal /ions have an 

 interesting arrangement in this species. In one of the three 

 examples no pores were missing from the intersegmental groove 

 v./vi. onwards. Iu another, one was not visible externally and 

 internally, the muscles, which are present in every case, running 

 from margin to margin of the successive pores, were exceedingly 

 feeble at this point. In the third example, which I did not open, 

 there was no doubt of the fact that the dorsal pores between 

 segments x./xi. and xi. xii. were absent : for in that worm the other 

 pores happened to be particularly conspicuously distended. There 

 is thus in the present species a series of stages which culminates 

 in the loss of the two dorsal pores immediately preceding the 

 clitellum. In B. moorei, as has been stated, the same pores are 

 absenl ; but it may be of course that other examples would show 

 some trace of their presence. I should observe that the muscle- 

 whose function it is to distend the pores are exceptionally well 

 developed in this species, and that the feeble muscles running from 

 the places which should be occupied by the missing dorsal pores 

 ended where the pores should be, and did not, as in B. iu>><h-,'>. 

 continue their course over this spot without a break. 



The seta have the usual strictly paired and ventral position. 

 The individual seta? are very plainly ornamented, as is the case 

 with other species; the ornamentation is in the form of slight 

 ridges over the distal end of the seta. The seta as a whole is 

 rather straight, and has often a somewhat peculiar ending in it > 

 epidermic sac, which is illustrated in the accompanying drawing 

 (text-fig. 1 I. p. 200). The seta- cannot be considered to be small 

 p1 proportionately, the worm being exceptionally large. 



The emeUum i- largely composed of segments whose mutual 

 demarcations have been to a great extent obliterated ; but in fronl 

 t.f. and behind, this region are two segments which belong to the 

 clitellum, though they are not bo thoroughly amalgamated with the 

 middle segments as the latter are with each other. Tin- clitellum 

 extends from segmenl xii. to xxiii. inclusive, and is thus longer than 

 that of B. moorei. Tin- ventral Burfaoe which bean tin- several 

 male pores is deeply depressed as shown in the drawing (te\t- 

 fig. l.">. p. 2 



Tin- figure >> I>. moorei ^liows the tesselated appearance <>f tin 

 integument in the region of the male pores; this appearance is 



