THE ENTOMOLOGIST. 61 



I have called it, varies infinitely in its character: in the 

 larvae of Lepidoptera it is thin, soft, and flexible in the 

 extreme ; while in crustaceans, -particularly in the claw of an 

 aged crab, it is so thick, solid, and calcareous, that it can 

 only be broken by a smart blow with the hammer. Between 

 these two opposites of extreme thinness and extreme thick- 

 ness, every conceivable intermediate occurs; but whatever 

 difference exists in this respect all exo-skeletons agree in 

 being repeatedly shed and renewed during life-time. The 

 process of moulting is common to most animals: the bird 

 loses and reproduces its feathers; the suckler its hair; but 

 in exosteates this exuviation extends to the whole covering: 

 this is shed entire, and not only to the covering, for the 

 exuviation extends to the interior, but those organs which 

 are most intimately connected with life share the same fate 

 as the exo-skeleton, of which they actually seem to form part, 

 and are cast off like our old clothes and replaced by a new 

 suit. I have been particularly interested in observirjg how 

 complete is this internal, as well as external, exuviation in 

 crabs, crayfish, and lobsters, the discarded garments of which 

 form most beautiful objects to examine, showing that even 

 the breathing apparatus to its most minute parts is cast off", 

 and replaced by a new one secreted within the body of 

 the animal. [These are the Ariiculata of Cuvier.] 



3. Anosteate animals, which have no bones at all, but 

 which have the power of building a house or shell for 

 protection out of material secreted by their own body. I say 

 have the power of doing so; but they do not always exercise 

 the power, very many species having neither bone, shell, nor 

 any substitute for these at any period of life. [These are the 

 Mollusca of Cuvier.] 



4. Acfininte animals, which have their several organs 

 arranged in a radiating fashion round a centre, like the star- 

 fish. The other divisions have not this radiating arrange- 

 ment of parts, but are what is called bilateral, that is, they 

 have both sides alike. [These are the Radiala of Cuvier.] 



The second of these divisions is that to which the sawflies 

 belong; but these require further division. 



In my Familiar Introduction, published in 1841,1 adopted 

 Latreille's name of Condylopa for this province, but 1 now 

 prefer to propose an entirely new one — Exosteala ; its contents 



