Proceedings of the General Meetings for Scientific Business of the Zoological Society of London 1892

Page 756

668 MR. F. E. BEDDARD ON NEW [Dec. 20, the phrase " as a rule more than one gizzard." According to this definition m y Acanthodrilus multiporus should be referred to the genus Benhamia ; and yet it differs from the African species (Africa is at present the headquarters of the genus) in a number of cha­racters : there are no penial setae ; the calciferous glands are limited to a single pair ; the dorsal vessel is double; the setae are not strictly paired, but separated by a little distance. There are two other species described in the present paper which agree with A. multiporus in these points; a fourth species, Acanthodrilus antarcticus, agrees with A. multiporus in most of these characters, but not in all. It has penial setae; the two pairs of calciferous glands are in segments xv., xvi., and there is a smaller gland in xiv.; only the single gizzard and the distant setae distinguish this species from the majority of those assigned by Michaelsen and others to the genus Benhamia. In spite, however, of the near resemblance of this particular Acanthodrilid to Benhamia, I a m not inclined to refer it to that genus. In the first place it is possible that Benhamia schlegelii, which is stated to have but one gizzard, has really two; the two gizzards in this genus are often so close together that it is not a little difficult to make out that they are really two; the interval of soft-walled oesophagus between them is reduced to the lowest terms in many cases. In the second place, Acanthodrilus antarcticus is so like A. multiporus in other particulars that it would be doing violence to their obvious relationship to separate them1. Taking into account also the distribution of these species it seems reasonable, now that the old genus Acanthodrilus is being broken up, to associate the N e w Zealand species here referred to into a genus distinct from Benhamia, which may be termed Octochcetus. It will be thus defined:- Octochaetus, nov. gen. Prostomium not continued by grooves on to buccal segment; clitel­lum xiii.-xix. (xx.); male pores on prominent papillce; setce distant; ventral setce present on segment xviii. ; a single gizzard in vi., or v. and vi., or v.; calciferous glands one or two pairs, in xvii., xviii., or xv. and xvi. ; typhlosole well developed; nephridia diffuse, a mucous gland present; dorsal vessel double from seventh segment onwards ; diverticula of spermatothecce very minute.-Distribution: New Zealand. There is another character to which comparatively little attention has been paid, which may prove to distinguish the genera Benhamia and Acanthodrilus. In the two species of Benhamia described in the present paper, as well as in B. stuhlmanni (for an opportunity of examining which I am indebted to Dr. Michaelsen), there are no setae upon the xviiith segment where the ventral pair should 1 It may turn out that the position of the gizzard distinguishes my genus Octochcetus from Benhamia; I a m aware that Eosa speaks of the gizzards of B. scioana as occupying segments v. and vi.; this is at present the only excep­tion to the rule that in Benhamia the gizzards are a segment or two further back.