1866. | Loology and Animal Physiology. 303 
a note on the Lepidosirens (Protopterus annectens of Owen), 
which have been living in the Menagerie of the Museum of Natural 
History. Up to the present time, the only period at which the 
Lepidosiren had been observed was when it quitted the peculiar 
cocoon of mud—formed by itself—in which it was frequently 
brought to Europe from the Senegambia. M. Dumeril has had 
the opportunity of observing the animal form its cocoon, and by 
producing an artificial “drying up” of the aquarium im which the 
Lepidosirens were kept, has succeeded in imitating the conditions 
under which they are met with in the African rivers. He establishes 
the facts, that the cocoon is used as a protection under these cir- 
cumstances, and is formed by a copious secretion of mucus from the 
surface of the body, and has no vegetable matters-in it. The fish 
fed on earth-worms, and the peculiar cry, observed already by Mr. 
M‘Donnell of Dublin, was uttered by one of the specimens at the 
Jardins des Plantes, when a portion of its cocoon had been broken. 
The remarkable researches which have been going on during the 
last year in Germany, relative to the asexual reproduction of the 
larvee of flies belonging to the genus Cecidomyza, are well worth 
the attention of all English naturalists; and it ought not to be long 
ere some of our own observers add their testimony to the evidence 
accumulated by our laborious continental friends. The first 
observations made on this subject were not published for some 
two years after they had been made, since the facts recorded 
by the naturalist who observed them appeared to the editors 
of the ‘ Zeitschrift fur Wissenschaftliche Zoologie’ to be almost 
incredible. It was in the winter of 1861-1862, that Professor 
Wagner of Casan communicated to Von Siebold some very re- 
markable observations on the reproduction of certain insect 
larve. These larve he found m great numbers in the bark of a 
dead elm-tree, and observed that they were filled with other 
smaller larvae, which completely resembled them. He at first 
thought this a case of parasitism ; but afterwards came to the con- 
clusion that he had here an instance of reproduction by insects 
which were themselveslarvz. Professor Wagner carefully followed 
up his first observations, and described in detail the larve and the 
perfect insect. This case of “alternation of generations,” as it is 
called, Herr Wagner considered a simpler one than that of the 
Aphis. He compared it to the propagation of the Cestode and 
_Trematode worms, basing his analogy on the fact that in the Dip- 
terous larve he had not discovered special organs of reproduction. 
Professor Pagenstecher of Heidelberg then published some re- 
searches on the larvee of an allied insect; he was able to confirm 
the general accuracy of Professor Wagner’s conclusions, but differed 
from him with regard to the production of the germs and a few other 
details. The larve observed in this case were obtained in immense 
