160 Miscellaneous. 
When using this piece of apparatus, the light should be opposite 
to the small aperture (a), and in a position at right angles to the body 
of the microscope. When the lamp is used alone, an image of its 
flame will be seen upon the object ; but the whole field of view may 
be illuminated, or unilateral light may be obtained, by placing a 
small condenser in different positions before the lamp. 
Under this method of illumination, which is available with the 
highest powers, the appearances presented by objects are very re- 
markable, and they vary exceedingly according to the character and 
condition of the specimen. It is in all cases best to have the object 
uncovered. The subject is of great importance and interest, and re- 
quires thorough investigation; but this, from the moderate cost of the 
piece of apparatus (10s. 6d.), is within the reach of every microscopist. 
Observations on some Lepidosirens (Protopterus annectens, Owen) 
which have lived inthe Menagerie of Reptiles in Paris, and formed 
their Cocoon there. By A. DuMERIL. 
M. A. Duméril has observed the formation of the cocoon by two 
specimens of Lepidosiren living in the Menagerie at the Jardin des 
Plantes. About the 20th February last, these two animals showed 
indications of a desire to shelter themselves in the soft soil at the 
bottom of the aquarium ; and as previous specimens had died, owing 
to the necessary change of conditions not being realized for them, 
the water was nearly all drawn off from the aquarium, so as to leave 
the mud at its bottom as nearly as possible in the same condition as 
the rice-fields inhabited by the Lepidosiren at the approach of the 
dry season. In three weeks the ground gradually hardened, forming 
a mass with fissures in several parts; no trace of the animals was to 
be detected. 
The fissures in the mass of dried mud enabled portions of it 
to be removed; and the two Lepidosirens were found, about eleven 
weeks after their disappearance, enveloped in regular cocoons. The 
block of dried mud, which is preserved in the museum, exhibits a 
cavity moulded upon the cocoon, with the walls perfectly smooth 
and lined with a strongly adherent portion of the cocoon. 
This cocoon is produced by a mucous secretion. Its brown 
colour might lead to the supposition that it is formed of dried leaves ; 
but when examined by Professor Decaisne, it presented no trace of 
vegetable structure ; and when burnt, it diffused the characteristic 
odour of animal substances. 
The Lepidosirens, when desirous of burying themselves, emit an 
abundant mucosity from the surface of the body. This coats and 
agglutinates the portions of the soil which they traverse, so that the 
walls of the subterranean canal made by each animal and remaining 
open after desiccation are smooth and appear polished ; then when the « 
animal stops, this exudation acquires the consistency of amembranous “|, 
envelope. The Lepidosirens when examined by M. Duméril were 
still alive, as was proved by their slight movements when touched ; 
they have since died.— Comptes Rendus, January 8, 1866, p. 97. 
