12 



In the female the oviducts opeu upon the coxopodites of the 3rd or ante^ 

 penultimate pair of thoracic legs. 



As already mentioned the 1st pair of abdominal appendages are modified to 

 assist the reproduction of the species. 



The eggs when laid are attached to the 2nd-5th pairs of abdominal 

 appendages of the female, and the young when hatched do not differ greatly from 

 the adult in form. 



We have no evidence on this point, but from the observations of Spence 

 Bate upon the common shore-crab of England, of Coste upon the crayfish and 

 certain crabs, of Andrews on Cambarus, of Wilson on Cancer pagimcs, and of 

 Brandes on Galathea and Eiqmgitrus, we may probably conclude that the eggs 

 are fertilized before they are laid, as in the case of the air-breathing Arthropods. 



12. Of Moulting or Exuviation. 



In its growth from the young to the adult stage and even beyond it, the 

 exoskeleton is periodically moulted. 



At each moult the entire cuticle of the body and its appendages is shed 

 bodily like a mould, and with it the lining membrane of the stomach and the 

 gastric teeth. 



After casting its exoskeleton, the animal remains for some days soft and 

 flabby, until the new cuticle hardens. 



It seems probable that although this process of moulting takes place 

 periodically throughout the greater part of the life of the animals of this class, 

 yet that at last a limit of growth is reached and exuviation ceases : for we 

 often find old crabs encrusted with barnacles and tubicolous annehds which have 

 evidently been attached for a long time. 



The Decapod Crustacea have also a certain power of renewing appendages, 

 or parts of appendages, that have been accidentally lost. From the stump of 

 the lost part a bud grows out, which in course of successive moults acquires 

 the form of the lost part. In consequence of this facility of repair, these 

 Crustacea will often voluntarily, on sufiicient occasion, discard an appendage. 



On tbe general morphology and organization of the Decapod Crustacea the following works 

 must be consulted : — 



H. Milne Edwards, Histoire Naturelle des Cnistaces, Vol. I. 

 De Haan, Fauna Japonica, Crustacea. 



Dana, Uuited States Exploring Expedition, Crustacea, Part I. 

 Bell, History of British Stallc-eyed Crttstacea, Introdaction. 

 HcxLET, THE CRAYFISH (International Scientific Series). 



Boas, Stndier over Decapodernes Slxgtskabsforhold (Vidensk. Selsk. Skr., 6 Ra?kke, naturvid- 

 og matheraat. Afd. I. 2. Kjobenhavn, 1880). 



