300 Bibliography. 
Ehrenberg’s generic characters, as well as Kittsing’s classification of 
the Diatomacee into Astomatice and Stomatice are founded on errors 
vissima,” by Ehrenberg and by Kiitsing, we do not hesitate to assert 
that not one of them is smooth. In fact, a Diatomaceous shell on 
test objects furnished by the Naviculm. ; 
In connection with this subject, we quote the following remarks in 
which the difficulty of resolving the markings on the Diatomaceous 
test objects is greatly overrated. ‘The authors state that ‘* those who 
make the structure of these shells a special study, require from forty 
to fifty minutes manipulation with a. first rate instrument, and all the 
modern appliances for obtaining intense oblique light, before they can 
shew certain strie or dots on a well known specimen.” we 
know by numerous trials made with Spencer’s objectives upon the most 
difficult test object now known, viz. the Grammatophora from Prove 
the field of view, two minutes is a very large allowance of t 
exhibition of its markings by sunlight, and this too, withou 
ingenious appliances for oblique illumination, on which the 
artists have lately devoted so much labor. gee 
e regret to see numerous typographical errors in this — ‘of 
among others one on page 102 which deprives Spencer of the er ve 
30° of aperture beyond what is there stated. Instead of bis objec 
having an angle of 147° as there stated, it should be 174°". “ 
Although we have thus pointed out some faults of this edition, 
yet can sincerely say that there is no work extant in which so 
valuable information concerning the Infusoria can be found; 
microscopist should add it to his library. ae some 
A. On the Origin of the Forms and Present Condilion of Aus 
the Clusters of Stars and several of the Nebula ; by SrErzEx from 
ANDER, Prof. Math. and Astron. in the College of New Jersey, (Tt 
Astronomical Journal, Nos. 36 to 44, 1852.) —The gener by 
the recent tel 
Some are simple elliptical clusters, with a brighter center; 
sist of two or three rings with an irregular fringe to the ext 
are literally broken rings; others are like dumb-bells; 
# See this Journal, 2nd Ser,, vol. xiii, p. 31. 
