CLASSiriCATION OF THE MAIOID CEUSTACEA. 643 



The carapace is subtriangular. Rostrum usually simple (bifid in Ste- 

 norhynchus). The merus joint of the outer maxillipedes 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 are placed at the head of 

 the Maioidea on account of the close approximation of the eyes 

 and antennae and their separation from the rest of the body by 

 the constriction of the postocular portion of the cephalothoras ; 

 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 ivith the palm elongated, cylindrical. Ambulatory legs ex- 

 tremely long. 



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

 Carapace smooth, even above. Antennae concealed beneath the 

 rostrum. Type Leptopodia sagittaria (Fabr.). 



* Metopoeaphis, Stimpson. Carapace uneven above. An- 

 tennae long, flagellum exposed. Type Metoporaphis calcarata 

 (Say). 



§§ nostrum composed qftico spines, or very short and simple. No 

 postocular spine. .^^Anterior legs with the palm shorter, inflated. 



Stenoehtnciius, Lamar ch {Macropus, Latr., part. ; Macro- 

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

 of two slender contiguous spines. Type Stenorhynchus rostratus 

 (Linn.). 



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

 Achceus Cranchii, Leach. 



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

 outer maxillipedes and dactyli of the ambulatory legs are subject 

 to much variation in the exotic species. 



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

 stomian regions naked. Type Podochela grossipes, Stimpson. 



PoDONEMA, Stimpson. Eostrum simple, rounded, excavate 

 beneath, and hood-shaped. Pterygostomian regions with lamelli- 



nv 



