7 90 CRUSTACEA. 



men being usually more elongated and freer in its articulations, and 

 the appendages below, although Isopod in arrangement, usually more 

 elongated, so as to approximate to the Amphipod type. And, as we 

 descend in the scale, we find in Liriope nearly the Amphipod cha- 

 racter. Through Praniza and Anceus the Cymothoid division de- 

 scends in scale. Both of these genera correspond to imperfect forms, 

 the two anterior thoracic segments being obsolete, and the legs but 

 ten in number. 



Some of the Anisopods appear to be inferior in character to the 

 Amphipods, although ranking between this, the lower group, and the 

 Isopoda. But this is no objection to our views, and is strikingly in 

 harmony with a general principle already explained. The Anisopoda, 

 as stated, constitute a transition group. There are two distinct types 

 of structure among the Choristopods, that of the Amphipods and that 

 of the Isopods, and between these, lie these connecting links, which 

 are the Anisopods. So, between the Brachyura and Macroura, there 

 are transition species, which are called Anomoura, not conforming to 

 either of the two great types among the Eubranchiate Decapoda, but 

 of an intermediate or transition character. And, as among the Ano- 

 moura, we find forms of less perfection as to structure, more sluggish 

 as to habits, and evidently lower in rank as regards intelligence, than 

 occur among the great majority of the Macroura, although these are 

 inferior in grade of structure ; so, in the Anisopoda, the most sluggish 

 of the Choristopods are to be found. These two transition groups are 

 analogous in this respect, and illustrate a fundamental truth of great 

 interest. 



The following is a synopsis of the families, subfamilies, and genera 

 of Anisopoda, as far as they are ascertained : — 



Subtribus I. SEROLIDEA, vel ANISOPODA CYMOTHOICA. 

 Fam. I. SEROLID^]. 



Appendices abdominales sex anticae liberae, subnatatoriae, quatuor 

 sequentes branchiales, bene laniellatae, ultimse ac in Cymotlwadis. 

 Antennae lmaa sub capite insitae. 



6. 1. Seeolis, Leach. 



