258 
ZOOLOGICAL LITERATURE. 
result of a clearly defined expression of those parts in which 
scientific carcinologists haye mostly hut one opinion. 
Frequent expressions of naturalists, both at home and abroad, 
have been conveyed to us that they consider this a very desirable 
object to be attained ; but there are few who would not rather 
undergo the risk of losing their observations in the indistinct 
terms that have become euphonious by long usage, than see 
them conveyed in words more accurate and defined, but, from 
their novelty, less agreeable. 
The use of terms that convey an erroneous impression, such 
as thorax and ahdomon, which are homologically dubious, if not 
incorrect, even in relation to Insects, and in Crustacea designate 
parts which bear but a crude and distant analogy to those they 
are named after in Mammalia, must necessarily be inconvenienl ; 
while most of the other parts are left much to the fancy of the 
dcscriber*. 
In the year 1849, M. Milne-Edwards, in an able and excellent 
essay in the Ann. des Sciences Naturelles,^ endeavoured to rectify 
this difficulty. He proposed a nomenclature based upon homo- 
logical inquiry, and formed upon classical authority. We have 
little doubt that the terminology of this great carcinologist 
would long ere this have been accepted by naturalists, but 
from the circumstance of the difficulty of applying terms so 
long and repetitive in their expression. 
A modification of the terminations of the nomenclature of 
Milne-Edwards, rather than wholly a ncAV one, was suggested by 
Mr. Spence Bate in his Report on the British Edriophthalma 
to the British Association for 1855. This having since been 
adopted by the authors of ^ The British Sessile-eyed Crustacea,^ 
we intend, when necessary, to make use of it in these pages, 
believing that thereby we shall be more certain in the trans- 
mission of our own and others^ ideas. 
Again, a systematic tabulation would not only accelerate the 
communication of ideas, but give a consistency to the symbols 
used, fr-om which they would derive an importance and signifi- 
cation that do not at present belong to them. We urge, there- 
fore, in pursuance of this idea, the invariable use of the same 
^ To explain ourselves more distinctly. That which Prof. Dana calls 
the ninth or last pair of appendages of tlie head in the Podophthalma, he 
calls the second of the thorax in the Edriophthalma, while Prof. Sars names 
them the third thoracic feet, and Prof. Milne-Edwards in his ‘ Histoire des 
Crustaces ’ (which has been the common handbook of carcinologists since 
its publication), and after him most authors, term the external or third pair of 
maxillipeds (“ pattes-machoires externes”) in Podophthalmous Crustacea, and 
the second thoracic pair of feet in the Edriophthalma. We consider them, 
in accordance with the last writer’s opinion, to be the appendages of the 
second somite of the pereion (thorax), and shall invariably specify them as 
the second pair of mathopocla, since, though appendages of the pereion, they 
are in a large number of dillerent families of Orustacea organs attendant on 
the mouth of the animal. 
