1G4 MisceUaneous. 



lUum, presents all the same cliaractei*s as D. macrostomum, from 

 which it ditlors only in size. Its length is from j to 2| lines, 

 while that of D. tnacrosiomum is only 4 to * Hue. These two forms 

 would therefore seem to constitute only a single species, which 

 attains larger dimensions in the Waders than in tlie Passerine 

 birds. 



The author concludes with some remarks upon the singular mirae- 

 tism presented by the Leiwochloridium, the resemblance of which 

 to the larva of an insect cannot fail to strike all who examine that 

 singular parasite. In his opinion, this resemblance, destined to de- 

 ceive insectivorous birds, has a teleological significance; for it does not 

 svTXC for the protection or preservation of the creature, but rather 

 leads to its destruction. It is true that this destruction is associ- 

 ated ■with the development of the larva) contained in it ; " but," 

 says the author, " no one can suppose that our Leucochhrid'uun 

 thus sacrifices its own existence to secure that of its progeny." 

 Agreed ! but no naturalist has ever asserted that mimetism was 

 due to an effect of the will of the creature that imitates. It shows 

 a very erroneous conception of the theory of mimetism, and conse- 

 quently of that of selection, to suppose that it ascribes the modifi- 

 cations of the species to voluntary actions of the indinduals ; and we 

 are sorry to see Dr. Zeller make use of the interesting facts that 

 he has discovered in support of such reasoning. In the great 

 struggle for existence the species is all, the IndiNndual almost 

 nothing ; and what can be more favourable to the preservation of 

 the species than this deceptive imitation which leads to the sacri- 

 fice of an individual without organs, such as Leiicochloridium, in 

 order to secure to the larvoe of the Distomum their transportation 

 into the intestine of an insectivorous bird, where they can acquire 

 their definitive development and become fitted to reproduce their 

 kind. — Zeitschr. fiir iviss. Zool. vol. xxiv. (1874), p. 564; Bill. 

 Univ., Bull Sci.' 1874, p. 366. 



TTie Diatomece of the Carboniferous Period. 

 By Count F. Castracaije. 



The author believing that, although hitherto undetected, Dia- 

 tomeae must have existed at the time of the formation of coal, hit 

 upon the ingenious expedient of examining with the microscope the 

 ashes of coal, instead of the thin sections previously studied. In 

 this way he has succeeded in ascertaining the presence in coal, 

 received from Liverpool, of a great number of species of Diatoms. 

 Most of them belong to freshwater genera or species; but the 

 presence of marine species mixed with these seems to prove that 

 the ground in which this coal was formed was in more or less 

 frequent communication with the sea. — Actes de TAcad. Pontif. 

 des Nuovi Lined, February 1874; Bibl. Univ., BidJ. Sci. 1874, 

 p. 376. 



