12 BRITISH ENTOMOSTRACA. 



M. Milne Edwards, in his excellent work on the Crus- 

 tacea,* adopts the organization of the month as the basis 

 of his arrangement also. He divides the great class 

 Crustacea into three sub-classes. The first two of these 

 have an apparatus especially provided for laying hold of 

 the substances destined for their food ; while the third 

 has no such special organization, their masticatory organs 

 being the same as their organs of locomotion. The first 

 sub-class is that of the Maxilles, or those whose mouth 

 is fm'uished with organs for mastication. The second is 

 that of the Sugeurs, or those whose mouth is furnished 

 with an apparatus for sucking ; and the third is that of 

 the Xyphosuriens, or those whose organs of motion are 

 the same as the organs of mastication, and which differ 

 in many other points also from the first two. The 

 Maxilles he again divides into four legions : 1st, Podoph- 

 thalmiens, containing the orders Decapodes and Sto- 

 mapodes ; 2d, Edriophthalmes, containing the orders 

 Amphipodes, Isopodes, and Loemipodes ; 3d, Branchio- 

 podes, containing the orders Cladoceres and Phyllopodes; 

 and, 4th, Entomostraces, containing the orders Ostrapodes 

 and Copepodes. In this arrangement, the last two 

 legions of the Maxilles, the Branchiopodes and Entomos- 

 traces, correspond exactly with Latreille's first order, the 

 Branchiopoda, and form a very natural group. The sub- 

 class Suceurs, he divides into two legions, the Parasites 

 nageurs, containing the orders Siphonostomes and Ler- 

 neens ; and the Parasites marcheurs, containing the order 

 Araneiformes. The last sub-class, the Xyphosuriens, con- 

 tains the single order Xyphosures. In this method we 

 see the Lerneae constitute a portion of Latreille's Psecilo- 

 poda, into which they were refused admittance by him. 

 They were placed by Cuvier, in his ' Regne Animal,' 

 amongst the Zoophyta, and in general, till within a few 

 years, they were classed by naturalists amongst the 

 Vermes. Desmarest showed the relations they had with 



* Hist. Nai. des Crustacea ; suitcb a Buffon, 1831-10. 



