54 CRUSTACEA. 



idea of the gradal relations of the groups. I give only the prominent 

 and obvious lines of relation, and not the many mterliukings of affini- 

 ties or convergences between the several lines. 



BRACHYURA. MAIOIDEA. MAHNEA. LEUCOSOIDEA. 



PARTIIENOPINEA. X3ANCROIDEA. 



/ | GRAPSOIDEA. 



ONCININEA. CORYSTOIDEA. CTCLINEA. 



I I I I 



vr/MnrrMTT) A fDROMIDEA. 



ANOMOURA. JAnom. Maiidica. 



/ BELLIDEA. 



\ Anom. Ca 



Cancridica. 



( PORCELLANIDEA. 



j HIPPIDEA. ( Anom. Grapsidica. 



I Anom. Corystidica. 



j LlTIIODEA. 



[ PAGURIDEA. 



' Anom. Maiid. degen. f GALATHilDEA. 



( Anom. Graps. degen. 



| RANINIDEA. 

 Anom. Leucosidica. 



MACROURA. THALASSIXIDEA. A8TACOS. 



This system of arrangement gives a very different view of the affi- 

 nities and gradations of species from the circles of De Haan, and, we 

 think, one that is more just to nature. Indeed, we deem the "circu- 

 lar system," as it is called, a splendid failure, in the effort of mind to 

 compass the kingdom of life. It was a brilliant scheme when first 

 brought forward, embracing much respecting the relations or affinities of 

 species that then seemed almost like a new revelation ; but as the first 

 glare has now passed, we can perceive that while it attempted to rid 

 science of the straight and rigid bars of artificial systems, it only modi- 

 fied the mode of coercion, by bending the bars into circles. There are 

 neither straight lines nor circles in nature, but main branching lines, 

 with subordinate branches, and almost endless reticulations or anasto- 

 moses, by curves of all kinds and of all grades of divergence and con- 

 vergence. 



According to the above explanations, we may consider 



The DKOMIDEA, as the Anomoura Maiidica. 



The LITHODEA and PAGURIDEA, as the Anomoura Maiidica degenerata. 



The BELLIDEA, as the Anomoura Cancridica. 



The HIPPIDEA, as the Anomoura Corystidica. 



The PORCELLANIDEA, as the Anomoura Grapsidica. 



The GALATH^IDEA, as the Anomoura Grapsidica degenerata. 



The KANINIDEA, as the Anomoura Leucosidica. 



We may distinguish thence four grades of the Anomoura. 

 I. ANOMOURA SUPERIORA Dromidea, Bellidea, and Raninidea : closely 

 Brachyural in most characters; eyes not anterior to inner antennas in 



