It is a very remarkable fact that in the genera _Criodrilus_ and _Alma_ the vent is dorsal in position instead of being surrounded as in earthworms generally by the last segment of the body. This fact might be put down to the near affinity between these two genera, were it not for the fact that _Glyphidrilus_ shows precisely the same state of affairs. These facts gain additional significance in my opinion from the fact that among the leeches which are now universally admitted to be allies of the earthworms the same position of the vent is met with. This abnormal position of the end of the alimentary canal may thus be fairly quoted in connection with structures modified by the aquatic life. Finally, and this seems to be very important, the only genus among the Megadrili which possesses gills is the Nile worm _Alma nilotica_. MARINE SPECIES. There are a few, but relatively speaking very few, worms of the order Oligochaeta which lead a marine life. And of these the majority are shore forms not extending into the waters of the sea. The most salient example, at any rate the best known perhaps, is the genus _Pontodrilus_, the name of which fixes its habitat, and was naturally given to it on that account. It was originally found on the sea shore of the South of France, and I have myself examined examples from Nice. The worm lives among bunches of sea-weed cast up by the sea, and which are thoroughly salt. Besides the two forms that have been met with in this Mediterranean region but which are united by Dr Michaelsen into but one species, other _Pontodrilus_ have been described from so many and such diverse parts of the world as the following. The West Indies (Bermudas, Jamaica etc.), the coasts of South America, of both West and Eastern Africa, the Red Sea, Christmas Island near Java, Sharks Bay in West Australia, the Hawaii Archipelago, Celebes, South West Australia etc. In fact there is no great tract of the ocean excepting the antarctic region where this genus is not to be found. It is possible however that this latter statement is not correct and that New Zealand ought to be added. But the species described from those islands, viz. _Pontodrilus lacustris_, is not a marine form at all as its specific name denotes; nor is it quite certainly to be included in the genus. On the other hand a form from the Chatham Islands in the same quarter of the globe, described originally as _Pontodrilus chathamensis_, is to be referred to the antarctic region. Altogether some dozen species of _Pontodrilus_ have been described by different naturalists; but quite recently Dr Michaelsen has reduced these to three only, which are _P. bermudensis_ (F. E. B.), _P. litoralis_ (Grube) and _P. matsushimensis_ (Izuka), with the doubtful addition of _P. lacustris_ already referred to. Whatever may be the ultimate verdict upon this question of species it is clear that the genus is widely spread upon the sea shores of the world and that forms from different regions