92 CRUSTACEA. 



tliat some of the higher Crustacea undergo no meta- 

 morphoses, whilst others closely related to them are meta- 

 morphotic. 



Various modes of distribution of this class have been pro- 

 |)Osed by different crustaceologists, which it would occupy 

 too much space to detail : I shall, therefore, proceed to give 

 a short sketch of that \\hich apj)ears to be the most natural 

 hitherto published, namely, that by Latreille in the second 

 edition of the Regne Animal, premising, that the distribution 

 of M. Edwards, founded primarily upon the manducatory or 

 suctorial nature of the mouth, appears to be less natural 

 than that given below^ 



CLASS CRUSTACEA. 



SECTION I. MALACOSTRACA. 



Shell of a sohd consistence ; legs ten or fourteen ; mouth 

 with a lal)rum, two mandibles, four maxillae, six or ten (ac- 

 cording to the number of legs) foot jaws. 



SUB-SECTION I. — PODOPHTHALMA. 



Eyes on footstalks. 



ORDER I. DECAPODA. 



Legs ten ; foot jaws ten ; branchiae in a cavity at the side 

 of the thorax. 



ORDER II. STOMAPODA. 



Branchiaj not inclosed beneath the shell at the sides of the 

 thorax ; legs more than ten. 



SUB-SECTION II. EDRIOPHTHALMA. 



Eyes not elevated on footstalks. 



ORDER HI. AMPHIPODA. 



Body compressed ; mandibles palpigerous. 



