1500 



CRUSTACEA. 



2. TORRID ZONE SECTION. 



1. MaiidaB, subfamilies Micippince, Chorininoe, Pyrince, 



2. Mithracidse, ..... 



3. Tychidas, ..... 



4. Periceridae, ..... 



5. Parthenopinea, .... 



6. Oncininea, ..... 



Torrid. 



16 



Temperate. 



3 



11 



6 



4 







43 



14 



28 



8 



2 







104 



31 



II. CANCROIDEA. 



1. TEMPERATE ZONE SECTION. 



Cancridae, 



Platyonychidae, 



Portunidae, subfamily Portuninse, 



Cyclinea, 



2. TORRID ZONE SECTION. 



Torrid. 

 



Temperate. 

 11 



2 



7 







15 







1 



34 



Xanthidae, 



Eriphidae, . 



Portunidae, excluding the Portunince, 



Podophthalmidae, 



Torrid. 



Temperate. 



129 



16 



44 



12 



52 



7 



2 







227 



35 



We have here two singular facts brought out. 



First, that the cold-water section of the Cancroidea embraces those 

 species that approach most nearly to the Corystoidea, and which we 

 have elsewhere shown to be the lowest in grade of the Cancrinea. 

 All have the lax character of the outer maxillipeds, which is a mark 

 of degradation in the Corystoids; and the Cyclinea are still nearer 

 that group. Many of the species moreover have the hind legs a 

 swimming pair, another mark of degradation. The Corystoidea, as 

 before shown, are two-thirds cold-water species. 



Second, that the cold-water section of the Maioidea contains the 



