CRUSTACEANS. 485 



sighted the compound eyes for more distant but perfect sight. They 

 appear to have a strong sense of smell. Many of them cannot swim, 

 but walk with more or less facility at the bottom of the water. It is 

 said, for instance, that the cavalier of the Syrian coast, Oxypoda 

 cursor (Fabricius), is named from the rapidity with which it traverses 

 great distances. 



Many systems have been proposed by different writers for the 

 arrangement of the Crustacea. That proposed by Mr. Milne Edwards 

 recommends itself, being founded on anatomical examination and 

 actual experiment made by himself and M. Audouin. He divides 

 them into two great divisions : I. "Those in which the mouth is 

 furnished with a certain number of organs adapted for the prehension 

 or division of food. II. Those in which the mouth is surrounded by 

 ambulatory extremities, the bases of which perform the part of jaws. 

 The first includes the MAXILOSA or MANDIBULATA, again divided 

 into Decapoda, having branchiae attached to the sides of the thorax, 

 and enclosed in special cavities. The Decapoda are divided into : 

 1. BRACHYURA, namely, the Crabs. Cancer, Porlunus, Grapsus y 

 Ocypode, and Doippe, belong to this group. 2. ANOMOURA, including 

 Droma, Pagurus, Porcellana, and Hippa. 3. MACROURA, including 

 the Lobsters, Astaeus, Palsemon, the Craw-fish, Palinurus. 



Stomatopoda, with external branchiae, sometimes rudimentary, 

 sometimes none. Thoracic extremities prehensile, or for swimming 

 generally, six or eight pairs. This division includes Mysids, Phyllo- 

 soma, Squilla, &c. 



The Cirripedia, or barnacles, are a very important division of 

 Crustacea ; they are found in all seas, and attach themselves to almost 

 every object in the sea; from the immovable rock to the moving 

 animal ; from the little Tunicata to the great turtle, or the whale. 



The goose barnacles, Anatifa, have a flexible peduncle. The 

 Balanoidea, or sea acorns, like oysters, are rooted to the spot on which 

 they rest in their infant days; without the power, like the goose 

 barnacle, of swaying to and fro like a pendulum, be their resting- 

 place what it may. 



One of the most remarkable animals of this class of Crustacea is the 

 Limulus Moluccanus the Molucca crab. They are distinguished by 

 a long serrated spine, which looks most formidable. They are in great 

 request in the mirkets of Java. Linnaeus thought that the fossil 



