78 J. D. Dana’s Mineralogical Contributions. 
P. S.—I regret that I should not have seen until now, when 
this paper is concluded, the important writings of Leydig on the 
subject under discussion. In his article “ Einige Bemerkungen 
aber die Entwickelung der Blattlause” in Siebold and Kolliker'’s 
Zeitsch. f. wiss. Zool. ii, 1850. p. 62, he speaks of his former 
observations in the Isis, 1848, iii, p. 184. These 1 have not seen, 
neither also a work to which he refers, of J. Victor Carus, (Zu 
naheren Kenntniss des Generationswecshels, Leipzig, 1849.) 
Leydig in his criticism of Carus’s views, expresses the opinion that 
the development of the viviparous Aphides is, histologically, like 
that of the Articulata in general. According to him, also, the germ- 
bodies undergo processes corresponding to those of impregnated 
eggs. ‘These statements of Leydig, who is an excellent observ- 
er, have induced me recently to repeat my observations ; but this 
afforded the same results as before, viz.: that the germ-bodies 
out of which are developed the viviparous Aphides, have no true 
histological identity with eggs. 
Arr. VIIL—Mineralogical Contributions ; by Jamzs D. Dana. 
1. Brooke and Miller’s Mineralogy. 
Te reviewer of this work in volume xv, page 41, mentions 
but briefly its importance in a crystallographic point of view. It 
is in. this department eminently an original work, the result of 
special researches on the crystallization of very many of the spe- 
cies, with the measurement and calculation of their angles. It 
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