232 HALF AN HOUR WITH CRUSTACEA. 



they represent actual feet, the Barnacle family go 

 by the name of Cirripedia. 



The true Crustacea, such as our lobsters, crabs, 

 prawns, shrimps, &c., differ very much among 

 themselves, whilst their young, or larva, are still 

 more unlike their parents, and bear a resemblance 

 to the young of Cirripedia. It is just possible that 

 our readers may be better acquainted with the taste 

 and flavour of the former animals than with their 

 general structure or anatomy, therefore a few words 

 of explanation may not be deemed out of place, 

 before we refer to some of the commoner members 

 of this group which the sea-side student may come 

 across in his rambles. None of the Crustacea have 

 real jaws, but instead, the feet are modified to carry 

 on the process of mastication. The typical crus- 

 tacean is supposed to have its limy shell formed 

 out of twenty-one pieces. These are distributed in 

 three divisions, called respectively the head, the 

 thorax, and the abdomen, seven in each. In many 

 cases, as in the crabs, &c., the fourteen segments of 

 the head and chest are fused, or run together into 

 one great piece, called the " cephalo-thorax." These 

 types of Crustacea sometimes go by the name of 

 " Stalk-eyed," on account of the eyes being borne 

 on pedicels, or stalks, capable of "moving about. 

 Another general name for them is Decapoda, or 

 " ten-footed," in allusion to the number of limbs. 

 The entire series is capable of being subdivided into 

 two great groups, called the macrura and the 



