AND THE LOWER ANIMALS. 95 



through its successive moultings, the number of seg- 

 ments and legs increases, without the other characters 

 being at all altered. When first hatched, our little 

 iulus is blind, but the eyes make their appearance 

 shortly after the locomotive organs, and increase in 

 number with the growth of the animal. We see that 

 in this instance there is no real metamorphosis, the 

 organism being completed, first by the addition of new 

 structures, and then by the repetition of existing ones. 



The Crustacea furnish us with similar phenomena. 

 In the little fresh- water prawn and in Garidina Bes- 

 marestii M. Joly observed that certain thoracic and 

 abdominal feet, and even the branchiae of the stoma- 

 chal pieces, do not exhibit themselves till after the 

 animal leaves the egg* Moreover, of the organs which 

 already exist, some are modified, whilst others, such as 

 the appendages of certain feet, are atrophied. We 

 see that even here there is an approach to metamor- 

 phosis in the ordinary acceptation of the term; but 

 on leaving this great section Macrurarf and passing 

 on to the Brachyura, J we shall find the phenomenon 

 even better marked. 



Is there any one of our readers who has spent a 



* "Etudes surles Moeurs, le Developpement et les Metamorphoses 

 d'une petite Salieoque, d'eau donee." — Annates des Sciences natu- 

 relles, 1843. 



t Literally, long-tailed. To this division of Crustacea belong the 

 lobsters, crayfish, shrimps, &c. ; in fact, all Crustacea whose abdomen, 

 commonly called the tail, is large, well-developed, and is employed 

 in swimming. 



% Literally, short-tailed. This group includes all crabs and 

 Crustacea whose abdomens are slightly developed, curved forwards, 

 and applied against the thorax, which is usually regarded as the 

 body of these animals. 



