CLASSIFICATION OF THE MAIOID CllUSTACEA. 



048 



The carapace is subtriangular. Rostrum usually simi)le (bifid in Ste- 

 nnrhynchus). The merus joint of the outer maxillipeilcs is truncated, 

 or elongated and rounded at its distal end, and articulated with the 

 next joint at its summit or at its antero-external or antero-internal angle. 

 The anterior legs have the palm cylindrical or inflated, fingers acute. 

 Ambulatory legs slender and very long. 



The genera included in this subfamily arc placed at the head of 

 the Maioidea on account of the close approximation of the eyes 

 and antenna? and their separation from the rest of tlie body by 

 the constriction of the postocular portion of the cephalothorax ; 

 the epistome is very long, and generally two or three of the post- 

 abdominal segments coalescent. 



§ Bostrum extremely long, simple. A postocular spine. Anterior 

 legs loith tlie jpalm elongated, cylindrical. Ambulatory legs ex- 

 tremely long. 



Leptopodia, Leach (Macropus, Latr., part. ; Pactolus, Leach). 

 Carapace smooth, even above. Antennae concealed beneath the 

 rostrum. Type Lep)toi)odia sagittaria (Fabr.). 



* Metopokaphis, Stimpson. Carapace uneven above. An- 

 tennuj long, flagellum exposed. Type JMetoporapliis calcarata 

 (Say). 



§§ Rostrum composed of two spines, or very sliort and simple. No 

 postocular spine. Anterior legs with tliepalm shorter, inflated. 



SxEXOEHTNcnus, Lamarclc (^Macropus, Latr,, part. ; Macro- 

 podia, Leach). (Plate XII. figs. 1, 2.) Eostrum elougatcd, 

 of two slender contiguous spines. Type ^tenorhynchus rostratus 

 (Linn.). 



Acn^us, Leach. Eostrum very short, emarginate. Type 

 AchcBUS Cranchii, Leach. 



The characters derived from the form of the merus joint of the 

 outer maxillipedes and dactyli of the ambulatory legs arc subject 

 to much variation in the exotic species. 



* PoDocnELA, Stimpson. Eostrum simple, acute. Pterygo- 

 stomian regions naked. Type Podochela grossipes, Stimpson. 



PoDOKEMA, Stimpson. Eostrum simple, rounded, excavate 

 beneath, and hood-shaped. Plerygostomian regions with lamelii- 



