Miscellaneous. 69 
enveloping membrane. In many Aphides these Amceboid cor- 
puscles undergo a further degree of evolution by their transfor- 
mation into small unequal bacilli, which are straight or diversely 
flexuose, immobile and colourless, and 0:005—0-:020 millim. in 
length. We might easily be led to regard them as a parasitic 
vegetable production, if we had not before our eyes all the suc- 
cessive phases of the transformation of these elements. More- 
over their rapid solubility in alkaline solutions constitutes a 
character which differentiates them completely from the micro- 
scopic Oscillatorie, with which they present the greatest resem- 
blance. Several times I have succeeded in seeing some of these 
corpuscles in the ovarian tubes, or forming small groups at the 
bottom of the terminal chamber of the ovigerous sheaths. 
In the third and last part of this memoir I shall investigate 
the phenomena of reproduction in the oviparous Aphides, and 
show how these are related to the viviparous generations which 
preceded them. 
MISCELLANEOUS. 
On the Metamorphoses of the Marine Crustacea. 
By M. Z. Gerse. 
Tue author gives the following summary of the conclusions to 
which his investigations have led him :— 
1. The larvee of the species belonging to the genera Maia, Pisa, 
Platycarcinus, Cancer, Xantus, Gonoplax, Portunus, Porcellana, 
Palinurus, Homarus, Callianassa, Crangon, Athanas, Palemon, 
Mysis, Ione, and very probably those of many other genera, undergo, 
immediately after their birth, a first moult, which gives them a form 
different from that which they possessed in the egg. 
2. None of the marine Crustacea of the division Podophthalma, 
or of the Edriophthalma, which I have observed has its organization 
complete at birth or possesses forms by which it might be referred 
to the species to which it belongs, and all are furnished with transi- 
tory appendages for natation, which give them a locomotion different 
from that which they will have in the perfect state : these appendages 
persist until the fifth or sixth moult, and become atrophied in posi- 
tion without falling off. 
3. It is only at the fifth moult in some, and at the sixth in others, 
and after having undergone modifications at each moult, that the 
general form of the adult and the external organs are complete. 
To these transitory external forms, so different from those of the 
perfect animals, and becoming modified at each moult, are due 
a multitude of false species and genera and doubtful families *, and 
even, as regards the larve of the Palinuri, an entire order to be 
eliminated. 
* The family of the Erichthide, in the order Stomapoda, appears to me 
to be chiefly founded upon Crustacea in the larval state. 
