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 



