Miscellaneous. baz 
0:005 m. in breadth at the level of the anterior branchiz. The 
crests had entirely disappeared. 
These external metamorphoses are accompanied by imternal modi- 
fications comparable with those observed in the Urodelous Batrachia 
when passing from the larval to the adult state. The anatomical 
examination of the hyo-branchial apparatus in the second metamor- 
phosed Axolotl (28th September) proved that the three inner 
branchial arches had disappeared, the external arch only remaining ; 
and this, deprived of its membranous denticulations and united by 
an articulation with the thyroid cornu, formed the posterior joint of 
the latter. Outside this piece the anterior branch of the hyoid is to 
be seen on each side. The basi-hyal was much developed, and in it, 
as in the other portions of the hyoid, ossification had commenced. 
These unexpected facts would almost lead one to suppose, with 
Cuvier, that the Axolotls, hitherto regarded as perennibranchiate 
Batrachia, may be the larvee of species destined hereafter to take a 
place in the group of those which undergo a metamorphosis and lose 
their branchie. If this be the case, the individuals with long external 
branchial tufts which have lived for nearly two years in Paris, and 
from which these young animals were procured, would only be larve, 
notwithstanding their power of reproduction*. But if this suppo- 
sition be accepted, how are we to explain the rapid metamorphosis of 
these animals of eight months old, when the individuals brought to 
France from Mexico in 1863 have undergone no change except an 
increase in size ’— Comptes Rendus, November 6, 1865, pp. 775-778. 
On the Multiplicity and Termination of the Nerves in the Mollusca. 
By M. Lacaze-Duruiers. 
Few animals are so richly provided with nerves as the Mollusca ; 
hence, when they are studied anatomically, it is difficult to under- 
stand the name of Apathique which Lamarck gave to the general 
group in which he placed them. 
I take Thetys leporina as an anatomical and histological type. This 
species presents in its tissues an abundance of nerves surpassing 
anything that could be imagined from what exists in the higher 
animals. In a general investigation of its organization I shall indi- 
cate in detail the very peculiar arrangement presented by its central 
nervous system. The only object of the present memoir is to make 
known the distribution of the nerves in the buccal veil, and their 
mode of termination in the barbules which fringe the margins of 
that organ. 
It is well known that, around the mouth, the lips of which are 
produced into a trunk, the Thetys has a large funnel-shaped mem- 
* M. de’ Filippi has found spermatozoids and mature ova in individuals 
of Triton alpestris, which, from the persistence of the external branchial 
tufts and the imperfection of their palatine dental system, appeared to be 
still in the larval or tadpole state (Archivio per la Zoologia, tom. u. 
pp. 206-211). 
