164 Miscellaneous. 
dium, presents all the same characters as D. macrostomum, from 
which it differs only in size. Its length is from } to 23 lines, 
while that of D. macrostomum is only 4 to 2 line. These two forms 
would therefore seem to constitute only a single species, which 
attains larger dimensions in the Waders than in the Passerine 
birds. 
The author concludes with some remarks upon the singular mime- 
tism presented by the Leucochloridium, 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 
serve 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 larve contained in it; “ but,” 
says the author, ‘no one can suppose that our Leucochloridium 
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 individuals ; 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 individual 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 Leucochloridium, in 
order to secure to the larve 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.—Zertschr. fiir weiss. Zool. vol. xxiv. (1874), p. 564; Bibl. 
Univ., Bull. Sci. 1874, p. 366. 
The Diatomee of the Carboniferous Period. 
By Count F. Casrracane. 
The author believing that, although hitherto undetected, Dia- 
tome 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 Acad. Pontif. 
ae Lincet, February 1874; Bibl. Univ., Bull. Sci. 1874, 
p. 376, 
