CLASSIFICATION OF CRUSTACEA. 1413 



part of this Report, and followed out through the subsequent pages. 

 The question, whether the eyes are pedicellate or not, upon which 

 the names Podophthalmia and Edriophthalmia are based, proves to be 

 one of secondary importance. And although still available in distin- 

 guishing almost infallibly the species of the first type, it is far from 

 rendering it necessary or natural to embrace together under a common 

 division the species that have sessile eyes (so-called Edrjophthalmia), 

 as done by most writers on this subject. 



The term Decapoda, in view of these principles, has a higher signi- 

 fication than has been suspected, since by expressing the number of 

 feet, it implies the number of cephalic annuli characterizing the 

 species. It would not be employing it inconveniently, therefore, if it 

 were extended to embrace all the Podophthalmia, or all species of the 

 first type, including the Mysis and Squilla groups. 



For a like reason, the term Tetradecapoda has a high significance, 

 as applied to the species of the second type. The position of the Tri- 

 lobita still remains in doubt. The Cirripedia and Entomostraca, third 

 and fourth types, stand properly on nearly the same level. 



On the following pages, we offer a review of the classification of 

 Crustacea, with the characters of the several subdivisions.* We first 

 present the characters of the higher divisions of the class, that is 



The SUBCLASSES, ORDERS, and TRIBES of Crustacea. 



* References and synonymy are omitted beyond, as they have been given fully in 

 other parts of the work. 



354 



