ARTICULATA. 115 
eyes are pedunculated. This order contains the largest of the Crustacea, 
as the lobsters and crabs. 
Latreille divides this order into two families, named sub-orders by Westwood 
and tribes by Burmeister, who includes them with the Stomatopoda in his order 
Podophthalma, and gives each of these an equal rank with the Stomatopoda, 
Isopoda, and other orders. Milne Edwards divides the Decapoda into three 
sections, admitting the Brachyura and Macrura, but separating certain 
anomalous genera from both, but chiefly from the Macrura, to form the third 
section Anomura (also written Anomoura, and meaning, the tae anomalous). 
In the Anomura the cephalothorax is large, the abdomen is not fully 
developed, and is much like that of the Brachyura. The second pair of 
external antenne are well developed, the external foot-jaws are generally 
like feet ; the three or four anterior pairs of feet are generally like those of 
the Brachyura, and adapted to locomotion, but the remaining ones are 
rudimentary, and in some cases used only for holding. 
Fam. 1. Paguride. The genus Pagurus (pl. 78, fig. 10), and several 
others of the same family, are remarkable for having the abdomen weak 
and soft, and the two posterior pairs of feet much reduced in size, and not 
‘adapted for walking. These animals are protected by the empty spiral shell 
of a mollusc, and as they increase in size they crawl along the beach 
hunting a larger shell, and various trials are made until a suitable one is 
found, the old one being again and again resumed, until the animal has 
suited itself. The abdomen and small feet enter the shell, and when the 
animal wishes to be safe, it withdraws itself so far that the head and robust 
anterior feet close up the aperture like an operculum. The posterior 
extremity of the body is curved, and with the posterior feet, adapted to 
maintain the shell in a proper position. One of the anterior pair of feet is 
larger than the other, and both terminate in a pair of pincers or chele. 
The sub-families are Pagurine, Hippine, and Porcellanine. 
Fam. 2. Rannide. In Ranina (2. serrata, pl. 78, fig. 9) the carapace 
is roughly serrated and transversely truncated before and narrowing pos- 
teriorly, producing a sub-triangular form. The anterior feet are cheliform, 
but not of avery large size, and the succeeding feet have the tarsus or last 
-articulation lamellar. The abdomen is narrow, of seven articulations, the 
last ones bent downwards. The species figured inhabits the East Indies, 
and is said to crawl up objects, even to the tops of houses. The sub-families 
are: Dromiune, Homoline, and Raninine. 
The Macrura are named from having a large and well developed tail or 
abdomen, ending in a fan-shaped fin (pl. 78, figs. 11-14)... The form is 
generally elongated, the carapace longer than in the crabs, and generally 
armed with a frontal spine; and the species, with few exceptions, are 
marine. The antenne are in general long, the first pair not received into 
a cavity as in the crabs; the mandibles are well developed; the walking 
feet are slender, and the first and second pairs frequently cheliform. The 
abdomen has seven articulations, of which the five basal ones bear the false 
feet. The caudal fin is formed of five pieces, the middle being an extension 
of the seventh or last segment, whilst the lateral ones arise from-the sides.of 
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