1903.1 MARINE FAUNA OF ZANZIBAR. 133 



supplement the earlier description and in a few details to correct 

 it As, however, a complete description, by Professor Mclntosii, 

 of specimens obtained by the ' Porcupine ' * has recently appeared 

 there is no need for me to do more than summarise the most 



definite points. ^ . , 



If the proportionate sizes of gills and tentacles were_ evei 

 approximately constant, surely they would be so in this species m 

 which their lar-e size is so characteristic. I find, however, that 

 the first gill, which is usually on the fourth foot, is often on the 

 fifth (Claparede and Grube give the fifth as the first gill-bearmg 

 foot ) The ringing of the gill-bases, upon which stress is laid m 

 Grube's tabulation^of the species, may be quite obvious or only to 

 be made out bv very careful examination. The anterior feet are 

 ringed very faintly. The last gill-bearing segment may be any 

 one between the fiftieth and sixtieth, and in one case it was the 

 fiftieth on the right side, the fifty-fifth on the left. The grills, 

 when laid forward, may extend either to the middle of the first 

 setigerous segment or beyond the front of the prostomium. ihe 

 buccal and first three setigerous segments are of about the same 

 length, but those succeeding rapidly shorten, so that numbers tour 

 to eight or twelve are the shortest in the body. 



The palps are very large, together forming an area greater than 

 that of the prostomium itself. Between them is a aeep and 

 narrow groove bounded anteriorly by a tubercle, which leads back 

 a little dorsally to the oesophagus, separation of which from the 

 jaw-apparatus is efi-ected by a pair of lips bearing large tubercles 



(PL XIY. fig. 1). , .. 



I do not find in either set of specimens any setfe corresponding 

 to Claparede's fig. 4d, pi. vi. of the ' Annelides du O. de^^Naples. 

 The compound setfe (" soies incompletement composees ) ot the 

 first three feet have invariably two hooks, which are quite distinct. 

 In the Naples specimens the comb-setfe have few teeth, and these 

 are remarkably broad and flat ; the capillary seta?, like the aciculj, 

 are gently bent near their ends, a fact which led Claparede to 

 describe them as being bordered or ending m a lance-head, iius 

 is not the case, though their sides are toothed, the teeth usually 

 being fine but sometimes large and coarse. 



The Zanzibar specimens agree with those mentioned above except 

 that the teeth of the combs are very fine and numerous, and that 

 the distal filaments of the gills are almost as long as the proximal. 

 In the Naples specimens the shape of the gill agrees wit.i 

 Claparede's figure in the shortness of the distal filaments, ihese 

 differences, though constant, do not warrant the creation ot a 

 specially named variety. 



At Prof. Mcintosh's suggestion I append an account ot turtnei 

 observations on the variation of the special anterior feet to which 

 importance has been attached by systematists. Prof. Mcintosh , 



* "Notes from tlie Gatty Marine Laboratory," Ann. & Mag. Nat. Hist. (ser. 7) 



"""t My ttiSiSue to Prof. Mcintosh for showing me his preparations and for 

 an opportunity of discussing them with hmi. 



