Not obviously related to any of the other families of Oligochaeta is the family Enchytraeidae. This consists of a very large number of species, which are placed in about a dozen genera, and whose habitat is nearly confined to the cold and temperate regions of the world. A large number of species for example have been described by Dr Eisen from Alaska, while others inhabit the verge of Patagonia. It is only a few which are found in warmer countries. There is for instance a solitary Enchytraeid in India and the neighbouring parts of Asia described by myself as _Henlea lefroyi_ but doubtfully of that genus according to Dr Michaelsen. I have also myself obtained another Enchytraeid from British Guiana. Apart from such rare exceptions the family is arctic or temperate in its range and is even met with upon the ice of glaciers. These little worms--they are very rarely of more than minute size--are both aquatic and terrestrial and inhabitants of the sea shore. They have four bundles of short often straight and somewhat stumpy setae; _Anachaeta_ is entirely without setae. That they bear some relation to the lowest group of Oligochaeta, that of the Aeolosomas and Naids, appears to be shown by the very anterior position of the spermathecae, _i.e._ in the fourth or fifth segment. The spermaries and ovaries on the other hand are in segments XI and XII. They are peculiar among the aquatic families in having complex glands appended to the oesophagus which recall the calciferous glands of the earthworms. The funnel of the sperm duct is extraordinarily deep and lined with glandular cells except in an apparently primitive genus from Lake Baikal. The remaining family of the Limicolae is that of the _Haplotaxidae_ which contains two genera, viz., Haplotaxis, better known as _Phreoryctes_, and _Pelodrilus_. These two genera overlap somewhat in their characters and it is in the present state of our knowledge rather difficult, if indeed possible, to differentiate them thoroughly. They are slender worms which frequent either damp earth or water and are thus somewhat intermediate in habit between the Limicolae and the Terricolae. The chief peculiarity of their structure lies in the fact that the sperm ducts are unprovided with any kind of terminal apparatus whatever, but open directly upon the exterior. Moreover there are generally two pairs of testes in segments X and XI, and in some species two pairs of ovaries in the two following segments. The small family is very widely distributed in more temperate regions, principally of the antarctic hemisphere. It occurs for instance in New Zealand, South Australia, the Cape, and in the northern hemisphere in Europe, Western Asia, and North America. CHAPTER II MODE OF LIFE