CRUSTACEA. 
265 
tliat this feature is a pceuliarity of male erustaeea generally. 
Another peeuliarity of the male Crustaeea he states to eonsist 
in the more abundant development of the membranaeeous hair- 
like appendages of the primary appendage of the first pair of 
antennie, whieh have been denominated auditory cilia by Mr. 
Spence Bate, and which Prof. Leydig and himself call olfactory 
organs. To such an extent does this difference exist in the 
Co])cpoda that Prof. Claus makes it a test of sexual distinction, 
and he thinks that this sexual difference is a strong evidence of 
their being organs adapted to the sense of smell. If this be 
the case, then, since the organ of hearing has, by anatomical 
investigation and definite experiment, been demonstrated to 
exist in the anterior pair of antennse, it must follow that the 
two senses are existent in the same antennse ; and since they 
are, as far as research enables us to speak, supplied only by a 
single pair of nerves, it must necessarily follow that the same 
nerves must carry both the sensation of smell and the sensa- 
tion of sound — a conclusion that is not consistent with our 
present knowledge. 
The author speaks of two species of Melita, M. messalina and 
M. insatiabilisy as living in great abundance under stones on the 
sea-shore, in one of which the coxae of the last pair of pereiopoda 
are produced into a peculiarly curved form, which distinguishes 
it from the females of the other species. He therefore argues 
that since such differences exist in animals that otherwise re- 
semble each other, so long as it is neither proved that this 
species particularly needs this arrangement, or that it would 
be more injurious than useful to other species, so long must we 
consider its occurrence in these few Amphipoda to be attribu- 
table, not to designing wisdom, but to fortuitous circumstances 
that have acted in some way on one species differently from 
what they have on others. 
V. Dr. Muller then treats of those Crustacea which, though 
allied to the marine forms in their structure, are capable of living 
not only out of the water, but in the burning sun of a tropical 
summer, and shows that these animals are endowed with two 
distinct organs of respiration, the one for water, the other 
for air. After being some time out of the water, and all the 
moisture in the branchial chamber exhausted (which is not 
until after it has been repeatedly aerated by being exposed on a 
fine network of hairs and again used in the branchial chamber), 
the animal raises the posterior portion of the carapace and 
admits air into a canal that exists, in Eriphia gonagra, poste- 
riorly to the last pair of pereiopoda ; in the Grapsoides, above 
them; in Ocypoda, which is exclusively a terrestrial genus, 
between the third and fourth pairs. This variation in tlie posi- 
tion of the opening to the air-chamber is in accordance with 
his conception of the truthfulness of Mr. Darwin^s theory. 
