Miscellaneous. 313 
Note on the Genus Chevreulius of Lacaze-Duthiers. 
To the Editors of the Annals and Magazine of Natural History. 
GENTLEMEN,—Mr. Alder, in the ‘ Annals’ for February last, has 
stated that the genus Chevreulius of Lacaze-Duthiers has been de- 
scribed twice before, by Messrs. Stimpson and Macdonald. 
I believe that the same genus is distinctly indicated by Ehrenberg 
(1828) in the introduction to his ‘Symbole Physicee’ (Mammalia, 
p- 3), thus: ‘.... quod formam animalium novam attulimus (Iho- 
dosoma verecundum) Ascidias bivalvibus Molluscis externa etiam 
forma adnectentem, Ascidiam scilicet tunica cartilaginea bivalvi in- 
dutam.”” These words seem to prove that the genus is found in the 
Red Sea. 
I take this occasion to call to mind a curious body described by 
Linnzus as an Asterias, but which perhaps may prove to be founded 
on a dried specimen belonging to Rhodosoma. 
Asterias (lunata) semiorbiculata. 
Corpus depressum, referens lunam dimidiatam, cum suis cornibus, 
adspersum undique punctis obsoletis, absque oris aut ani vestigio. 
(Linn. in ‘‘ Chinensia Lagerstrémiana,’’ ‘Amcenitates Academicee,’ 
iv. p. 256, n. 44. fig. 14.) 
The figure represents a crescent-shaped body, about 2 inches long, 
with some dispersed granulations on the surface. 
Perhaps, however, it is only an object of art, like the Corallium 
chinense on the same plate, which represents a piece of jade formed 
into a man on horseback. 
I am Gentlemen, 
Yours obediently, 
O. A. L. Morcu. 
Copenhagen, Feb. 27, 1866. 
On the Functions of the Air-cells, and the Mechanism of Respira- 
tion, in Birds. By Dr. Drosier. 
After brief mention of the additions made to our knowledge of these 
matters by numerous distinguished physiologists, the author remarked 
that still more remained to be done—a proof of the difficulty of the 
subject. Several of the commonly received views are quite untenable, 
—such as that the air-cells are intended to assist in supporting the 
bird in flight, by rendering it lighter, in consequence of the rarefac- 
faction of the air in the air-cells, and the hollow bones; and again, 
that the air-cells are a sort of second respiratory apparatus, so that 
birds may be described, as they were by Cuvier, as animals having 
a double respiration. In disproof of these views, it was shown that 
a pigeon weighing 10 ounces, or 4375 grains, would have its weight 
in air diminished by less than one grain in consequence of the rare- 
faction of the air in its air-sacs and hollow bones; so that the floating- 
power resulting from such rarefaction would be almost inappreciable. 
Again, the air-cells are bounded by delicate membranes, in which 
