ZOOLOGY AND BOTANY, MICBOSCOPY, ETC, 



505 



forward impossible to place them in the same order. Of the two sub- 

 divisions of the Mysidaceee — Mysidse and Lophogastridae — the latter 

 stand nearest the starting-point. The Cumacese have been derived 

 from a form which was closely allied to the Mysidae. The Hedrioph- 

 thalmata would appear to have arisen from forms intermediate between 

 the MysidsB and Cumacete ; they are, therefore, not to be regarded as 

 lowly forms, or as having only distant relations to the Podophthal- 

 mata, with which they are partly closely allied. But the Isopoda and 

 Amphipoda differ so much from one another that it is impossible to 

 include them in the same order. The Squillaceae occupy a very 

 isolated position ; they are most nearly — though still distantly — 

 allied to the EuphausidsB, but in some points they exhibit more 

 primitive characters than any other group of the Malacostraca. 



The author illustrates his view by a phylogenetic table, which it is 

 worth while to reproduce : — 



-'Amphipoda 

 Isopoda 



Cumacea 



Lophogastridse 

 Squillidce 



Decapods 

 Euphausid^ 



Phyllopoda 



And he gives also the following systematic table : — 



Sub-class Malacostbaca. 

 Order i. Euphausiacea. 



ii. Mysidacea|^^^-°'"^"^|- ^/sidf '*'''^^' 

 iii. Cumacea. 

 iv. Isopoda. 

 V. Amphipoda. 



• -n ;i (Sub-order i. Natantia. 



VI. Decapoda < •- -r. . x- 



(. „ 11. xieptantia. 



vii. Squillacea. 



In his remarks on the appendages Boas points out that the same 

 pair has often different names in different orders, while the same name 



