154 
NATURAL HISTORY. 
[N. ZOOL. GAL, 
by some of the ancients to be consentaneous inmates with the mollus¬ 
cous animal, and attached to it by mutual interest. The Fainted or 
Land Crabs ( Gecarcinus, Case 17,) live in holes in the earth, especially 
near burying- grounds, and only go to the sea during the breeding season; 
their flesh is considered a delicacy, but it sometimes proves deleterious. 
Besides the preceding, there are specimens of the Globular Crabs ( Leu- 
cosia, Case 19); Sea Spiders ( Leptopodia , Case 13), with their very 
long legs ; Crested Crabs ( Calappa), having the front part of the claws 
raised into a crest, and the hinder part of the shell projecting so as to 
cover the legs ; and lastly, those Crabs which have the two hinder pairs 
of legs placed on their back (Dorippe), and the Death's-head Crabs 
(Dromia , Case 19). 
Long-tailed Crustacea, (Cases 20, 22,) as the Lobsters and Shrimps, 
amongst which, those of the genus Hippa (Case 20) have the ex¬ 
tremity of the tail simple. The Soldier or Hermit Crabs ( Pagurus , 
Case 20) live principally in the cavities of sponges, and also in the 
mouth of spiral shells, occasionally altering the texture of the latter, by 
some unknown process, to such a degree as to render them quite soft, 
and easily penetrable by a common pin. Amongst these is a fine 
specimen of Birgus latro , (Case 20,) said to live on the nuts of palm 
trees. Also specimens of the Sea Locust ( ScyUarus ), the Rock 
Lobsters (Palinurus , Case 21), the Plated Lobster ( Galathea , Case 
20), and the Crab Lobster ( Porcellana ), which, from the shortness of 
their tails, generally resemble crabs in appearance; the Scorpion 
Lobster, ( Thalassina , Case 21,) which lives a great paid of its life on 
land, and destroys the new made roads in India by the excavations it 
forms under them ; Lobsters, ( Astacus , Case 21,) one of the specimens 
exhibited was pale red, nearly of its present colour, when alive; Shrimps 
(Palcemon , Case 22) varying greatly in size. 
The Stomatopodes or Sea Mantis, differ from the Decap odes in the 
head being horny and separated from the thorax, and in having only 
three pairs of accessory jaws, seven pairs of feet, and th£ gills on the 
abdomen; among them are different species of Squilla, the glass-like 
Alima , and the Phyllosoma , w 7 hich is scarcely thicker than a piece of 
paper, and nearly as transparent as glass; they are found in the ocean 
near the equator. 
The remainder of the Crustacea ( Edriophthalma ) have sessile eyes. 
The order of Arthrostraca ( Case 21) have a free head, and their body 
composed of a series of similar rings, the first seven of which are each 
furnished with a pair of feet, the following and last ones, (seven at most,) 
forming a sort of tail, ending in fins or filiform appendages. On the 
head are four antennas and a mouth composed of three pairs of jaw r s. 
The females carry their eggs between the scales in a kind of pouch 
under their thorax, and w 7 hen the young are hatched, they remain at¬ 
tached to the feet or other part of the body of their mother, until they 
have acquired strength requisite to swim about and provide for their own 
wants. They are all of a small size. A few 7 are found in fresh water, 
and few 7 er are terrestrial; some are parasitic on other marine animals. 
This order has been divided into three sections; some, as the Am- 
phipodes, have their jaws furnished with a palpus, w 7 hile the Lcemodi - 
podes and Isopodes are destitute of them. 
The order of Entomostraca, on the other hand, have a soft head, 
