140 THE ZOOLOGIST. 
Crayfish,’ its segments consist, firstly, of a basal joint, the coxo- 
PODITE, followed by the BASIPODITE, ISCHIOPODITE, MEROPODITE, 
CARPOPODITE, PROPODITE, and DACTYLOPODITE in succession. This 
limb may be taken as sufficiently characteristic to refer to when 
necessity requires such reference. 
In the Macroura the first pair of legs are generally developed 
into broad hands and forceps, the development of which is 
strikingly varied in the different genera and tribes; for in the 
Palemonide, for example, they are but slightly enlarged, the 
second pair being the larger. Again, in Nephrops norvegicus they 
are long, fluted, and tuberculated; whilst in Homarus marinus 
(= vulgaris) they are broad and massive. Perpetual discrepancies 
also exist in some, as in the case of Avius stirhynchus and Calli- 
anassa subterranea, where one hand is very primitive, whilst its 
fellow is well developed. In the Anomoura, again, this variety 
also exists, the Paguride being characterised by one being large 
and the other small; whilst in the Galathea they are symmetrical, 
though again differing in point of detail, some being spinous and 
others scaly. In the Porcellana they are broad and flattened, 
being, in the case of P. platycheles, fringed with hair on the outer 
margin. In the Brachyura they are symmetrical, but vary from 
being attenuated and smooth, as in Gonoplax angulatus, and the 
same, only spinous, as in Hurynome aspera, to being vertically 
broad and hairy, as in Atelecyclus septemdentatus, and massive as 
in the case of Cancer pagurus. In the Anomoura the last pair of 
feet are either rudimentary or, if developed, of little practical value 
for walking; whilst the corresponding pair in the family Portunide 
have the last joint paddle-shaped: hence this family are known as 
Swimming Crabs. Many species have the terminal hook extremely 
sharp. ‘This is particularly observable in the genus Pisa, where 
this sharp hook has the power of clenching its hold on such 
substances as branches of Alge, &c., much in the same way as do 
many parasites, especially Acari. 
Referring now briefly to the appendages situated in the front 
of the thorax, we find in the Podophthalma a pair of eyes fixed to 
stalks more less developed, and again exhibiting a remarkable 
variety of form, one species in particular, Gonoplax angulatus, 
having this stalk of considerable length. 
The antenne, like the eyes, consist of one pair, also varying 
greatly, and below these we find a pair of antennules; these 
