Miscellaneous. 239 readily give rise to mistakes. Cells of the animal detach them-selves from the mass, and remain scattered all round it. Some of these are finally dissolved, but others (or, at least, bodies which cannot be distinguished from them in appearance) begin to emit very delicate transparent filaments, resembling those oi Actinophrys. Some of these bodies even become encysted in the manner oi Actino-phryt and Amoeba. From these, four or five monociliated Monads are sometimes seen to issue : these are capable either of creeping in the manner of Amoeba, or of swimming by the agency of their fiagel-lum. These creatures are sometimes present in such great number, in the interior of dying SpongiU<e, that one might be led to regard them as masses of sponge-cells. We should then have to recur to Dujardin's notion that the Spongillee were merely masses of Ameeb^e inhabiting a sort of siliceous polypary. M. Lieberkuhn, however, shows that these bodies form no integral part of the Sponffilia, and that they appear also in great quantities in the ova of fishes and other animals when in course of perishing. But he does not settle the ques-tion whether the Monads are the embryos of these kinds of Amoebat or whether we are to consider them as parasites of these parasites. It it interesting to compare these facta with the observations made by Jaeger upon Hydra. It has been asserted that these animals are capable of breaking up into little unicellular Amoebiform creatures, which on their part can reproduce the Uyrlree. Is not this an ana-logous case of parasitism !nisinteri)reted ? — Millers drckiv, 1863, p. 717; Bibl. Univ. June 20, 1864, Bull. Set. p. 183. On the Geographical Distribution of the Annelida. By A. De Quatrcfages. Having completed a work on the Annelida which will form a portion of Roret's Suites d Buffon, M. Quatrefages has communicated to the Academy of Sciences of Paris some remarks upon the geo-graphical distribution of those animals. He observes that, although the imperfection of our knowledge of the species would render it premature to undertake any detailed investigation of the subject, it is possible to indicate certain general laws, some of which are of the more importance as they contrast strikingly with facts universally recognized in other groups. His results are as follows: — 1. The class of Annelida properly so called {Annelida Errantia and Tubicola) is in salt waters the geographical term corresponding to the land and freshwater class oi Erythrteina (Lttmbrici And Na'ides). 2. The class of Annelida has representatives in all seas. This is also the case with the two orders of which it is composed (Errantia and Sedentaria) ; in this respect the group under consideration may be said to fall under the general rules. '^. This cosmopolitism appears to extend not only to the lai^ genera which best reproduce the general type, but also to the most excep-tional subtypes, and even to those genera which might be supposed to be most characteristic. In this respect the Annelida differ from all the other groups which have been investigated from a geographical point of view. 4. Hence it results that the AnneUdan fauna does not appear to
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