REPORT ON THE ANNELIDA. 
57 
publications as those of Dr. Hansen on the Annelids of the Norwegian North Sea Expedition 
so lax in diagnosis and so indifferent to the value of the minute structure of the bristles. 
It is no argument to say that the bristles vary in each foot, and that the anterior differ 
from the posterior. Their variation in these parts respectively follows regular and definite 
laws, which, however, are very difficult of explanation, though their condition is palpable 
enough to every minute observer. In comparing species, each series of bristles from the 
same foot must of course be contrasted, and with a little care an average one in each case 
can readily be selected, without laboriously examining the whole. Every well-marked 
species has a character of its own. In order to exemplify the laxity in such 
descriptions it is sufficient to quote Dr. Hansen’s account of the feet in his Polynoe 
foraminifera, n. sp. “The pedal protuberances with two short lobes ; the ventral cirrus 
not reaching to the summit of the protuberance. The bristles normal in form, the dorsal 
shorter than the ventral, which a little below the simple arcuate j^oint are much more 
coarsely transverse-serrate than the former.” Familiarity with the Polynoidge is of little 
avail to the reader of these lines. Dr. Hansen’s figures, however, are of value in a 
critical revision. 
In the general structure of the group considerable advances have been made in con- 
nection with the segmental organs and ventral papillae. The authors who first called 
attention to the subject were Grube and Claparede, while Huxley also associated the 
papilla with the reproductive functions. Recently Mr. W. A. Haswell,^ B.Sc. 
Edin., carefully examined the structure of the parts in Australian Polynoidae, and 
pointed out the true position of the segmental organs, which open externally by the 
ventral papillae, through which he also saw spermatozoa issuing in one example, and he 
does not doubt that the ova issue by the same channel, and are directed by the currents 
of cilia to the cavities under the elytra where they undergo the earlier stages of develop- 
ment. He did not observe any apertures in the walls of the feet in the species examined, 
hlr. A. G. Bourne,^ B.Sc. Bond., subsequently described the same parts, giving a minute 
account of their structure, illustrated by excellent figures,- He is of opinion that the 
segmental organs open by a trumpet-like internal termination close to the ventral longi- 
tudinal muscles, and externally by the ventral papilla. Further, he thinks the generative 
products do not pass out by the latter aperture, but probably by sjDontaneous rupture of 
the body -wall. In connection with the external aperture, Grube ^ pointed out the 
occurrence of the remarkable ventral lamellse of Gastrolepidia clavigera on the site of 
the swelling at the base of the papilla. 
The occurrence of the pseudobranchial process on the dorsum of the foot in Achloe 
1 Proc. Linn. Soc. N. S. Wales, vol. vii. pp. 262 et seq. Mr. Haswell was good enough to send me some very 
beantifnl sections of these parts, and they hear out his descriptions. 
2 Trans. Linn. Soc. Land. (ZooL), ser. 2, vol. ii. pp. 352-354. Dr. Marenzeller, amongst others, had anticipated Mr. 
Bourne in regard to the identity of Lepidonotus clava, Mont., with Polynoe grubiana, Claparede. 
2 Annel. Fauna d. Philippinen, p. 43. 
(ZOOL. CHALL. EXP. PART XXXIV. 1885.) LI 8 
