216 Proceedings of the Royal Physical Society. 



term in the wider sense to include also the hepatics, that 

 they are most at home. Where we have moss we have 

 bdelloids, and usually in great numbers. Rarely does a 

 handful of moss, properly treated, fail to yield at least a 

 dozen species. It must not be supposed, however, that all 

 kinds of moss are equally productive. The pleurocarpous 

 section is very much better than the acrocarpous. Sphagnum, 

 as a rule, is populous, but Thuidium, Fontinalis, and certain 

 ffypna, among the true mosses, and Frullania among the 

 hepatics, usually give more variety. And as regards season, 

 autumn, winter, and spring are better than summer. 



The method of obtaining the bdelloids which I have found 

 most successful is a very simple one. The moss is washed 

 vigorously in a vessel of water ; then the water is strained 

 through a coarse silk net, and finally passed through a silk 

 net fine enough to retain all the rotifers. The coarse net, 

 for which I find a No. 6 bolting cloth suitable, retains all 

 moss stems, leaves, and the larger debris, but allows all but 

 the largest rotifers, such as Stephanoceros, to pass through. 

 In practice it is found most convenient to place the coarse 

 net inside the fine one, and to use them as the vessel in 

 which the moss is washed. When the coarse net is removed 

 the rotifers pass through into the fine one, and can then be 

 bottled and examined at leisure. They should be examined 

 as soon as possible, as many species invariably die within 

 twenty-four hours when kept in bottles, although others will 

 live for a long time. 



It is not definitely known whether any bdelloids, except 

 Discopus, have their ordinary habitat in the sea. Gosse 

 found Philodina microps in salt-water, but it has not been 

 again found. At Lochinver I found two species, which I 

 was unable to name, in the washings of seaweeds, and again 

 at Aberdeen a single example. These may have been casu- 

 ally introduced, or they may be, like some rotifers of the 

 other orders {i.e., Furcularia reinhardti), able to live in- 

 differently in salt or fresh water. 



On the 17th of November 1905, Mr Evans obtained some 

 fine moss-like seaweed at Morrison's Haven, on the south 

 side of the Firth of Forth. On washing it I found one 



