G64 MEMORANDA. 
cases are folded in a sheet of paper, in such a manner that 
about two inches of the paper extends beyond one end of the 
case, and the postage stamps are affixed to this free end, 
there will be no risk of damage from the obliterating stamp. 
It was suggested that additional security from local stamping 
would be given by pasting black paper round that portion of 
the package which contained the slide, and the address 
written on the free end of the paper. This would be the 
only white portion, on which consequently all stamping must 
be performed. A number of boxes and other contrivances 
for the transmission of slides, and which had passed through 
the ordeal of a journey, were exhibited ; some of which, in 
their shattered contents, gave evidence of failure. 
M. Eulenstein’s Series of Diatomacez.—Those of our readers 
who are more especially interested in the study of Diatoms, 
will be pleased to learn that M. Th. Eulenstein, of Stutgard, 
who is well known as one of the most active investigators of 
the subject, has undertaken the publication of two distinct 
series of specimens of Diatomacez. One series will consist 
of AUTHENTIC and ORIGINAL specimens; and it is intended 
to facilitate the identification of the numerous species estab- 
lished by foreign authors. The uncertainty of nomenclature 
which has pervaded all the writings on this subject since the 
works of Ehrenberg and Kiitzing is entirely due to a want of 
accurate knowledge of these specimens, which M. Eulenstein 
has spared no pains to obtain for the present purpose. 
Simultaneously with, but perfectly distinct from this series, 
M. Eulenstein intends also to publish another. series, which 
will form, as it were, a STANDARD collection of the various 
types of the Diatomacee, and will contain typical represen- 
tatives of nearly all the known genera, recent and fossil. 
Each series, as we learn from the prospectus, will be issued 
in five parts, each part containing one hundred species. The 
first part of the first-mentioned series will consist chiefly of 
specimens selected from the herbarium of Professor Kiitzing, 
and will explain many critical species established by that 
author in his ‘ Bacillaria’ and ‘Species Algarum.’ The sub- 
sequent parts will contain original specimens illustrating the 
works of Ehrenberg, Heilberg, Grunnow, Rabenhorst, and 
others. Besides the numerous new and rare forms which 
will be found in this series, it will furnish systematists with 
a correct index to many species hitherto misunderstocd, and 
