MACRUEA ANOMALA 149 



TRIBE I. ANOMALA. 



The pterygostomian regions are free from the epistome 

 and marked off from the back by a suture or continuous 

 furrow. The fifth pair of legs are generally weak, not fit 

 either for walking, swimming, or grasping food and prey. 



The tribe embraces five legions, Hippinea, Lithodinea, 

 Pagurinea, Porcellaninea, Galatheinea. 



Legion 1. Hippineci. 



The carapace is ovate or subquadrate, comparatively 

 smooth, the regions ill defined, the ' front ' broad. The 

 corneae of the eyes are small. The first antennae are in 

 general strongly developed, with one flagellum elongate, 

 the other of moderate size or absent. The second antennas 

 have usually a short flagellum and a massive peduncle of 

 four or five joints, with or without a movable acicle on 

 the second. The third maxillipeds are moderately broad, 

 sub-operculiform. The walking-legs have a flattened 

 terminal joint. The fifth pair are slender and filiform and 

 folded under the preceding pair. The sterna of the trunk 

 are linear. The pleon is partially extended, with the tel- 

 son large, longer than broad, and the preceding segment 

 carrying a pair of biramous lamellar appendages, not so 

 arranged as to form a rhipidura. The males have no 

 appendages to the pleon but those of the penultimate 

 segment. 



The members of this legion inhabit the shallow waters 

 of tropical and subtropical seas. They are divided between 

 the two families of the Hippidas and AlbuneidaB. 



Family 1. Hippidce. 



The third maxillipeds are sub-operculiform, with a bread 

 fourth joint ; the exopod is wanting. The first pair of legs 

 are sub-cylindrical and not chelate. The telsoiiis elongate, 

 lanceolate. 



This family includes three genera. 



Hippa, Pabricius, 1793, has been much restricted since 

 it was first instituted. It is now especially distinguished 



