76 Miscellaneous. 



long, soon elongates until it acquires a nearly square form, which it 

 retains. 



This mode of multiplication appears interesting, as it seems to show 

 the solvent action exerted by proteic substances upon cellulose mem- 

 brane and the part which they play in its regeneration, phsenomena 

 which, as may be seen, are not without analogy with those observable 

 during the evolution of spores, pollen, &c. Another fact vvorthy of 

 remark is, that in these formations the generation of the cells ex- 

 tends to all those contiguous to the parent cell of the stomate. — 

 Comjptes Rendus, 17th April, 1854, p. 744. 



Description of a new Genus of Bivalve MoUusca. 

 By H. and A. Adams. 



Genus Myrina, H. and A. Adams. 



Shell transverse, oblong, subequilateral ; valves closed, covered with 

 a horny epidermis, pearly within ; beaks subcentral. Hinge eden- 

 tulous, ligament internal, linear ; muscular impressions far apart, 

 pallial impression simple. Byssiferous. 



A single specie, for which we propose the name M. Denhami, was 

 discovered by the Officers of H.M.S. Herald, attached to floating 

 masses of blubber. 



On the Dimorphism of the Uredinese. By M. Tulasne. 



Since numerous observations have placed it beyond a doubt that 

 a vast number of Fungi possess reproductive bodies of several kinds, 

 there is in the history of the TJredinece a fact, which, I think, admits 

 of a more satisfactory interpretation than it has hitherto received. I 

 refer to the simultaneous presence or succession in the same sori of 

 two sorts of fruits (spores), which are attributed to different species. 

 Some mycologists see in this nothing but a cohabitation, which, 

 although frequent, is by no means necessary ; others suppose a com- 

 pulsory relation between the two Uredines, — that of a parasite with 

 its host. If the latter opinion prevailed, instead of four or five 

 Phragmidia and a few Puccinice, which would be parasitic upon 

 various Uredines, as is usually believed, we should have, as I have 

 convinced myself, a multitude of other Puccinice, the Uromyces, the 

 Pilularice, the Triphragmia, the Coleosporia, the Melampsorce, the 

 Cronartia, and no doubt many other XJredinece which I have not 

 yet been able to study sufficiently. Thus the Vredinece would not 

 only live, as is really the case, as parasites upon the vascular plants, 

 but they would also offer among themselves an example of parasitism 

 quite unknown in the history of organized bodies, as about a third 

 of their species would be charged with the nourishment of another 

 third. This parasitism would also present a very unprecedented cha- 

 racter, for it would prevail between plants almost identical with each 

 other, or at all events united by the closest affinities, whilst, even 

 amongst the simplest beings, there are generally well-characterized 

 organic differences between the parasite and its host. The parasitic 

 life attributed to the Phragmidia, the Puccinice, the Cronartia, and 

 other UredinecB, in relation to the Uredines proper, is therefore ^ 



