CLASSIPICATIOIT OP THE MAIOID CEUSTACEA. G61 



N"otwitlistanding the great dissimilarity of Mici/ppa and Picro- 

 cenis, which stand at opposite extremes of the series, a regular 

 gradation may be traced between the genera of this group. In 

 Picrocerus the broad and lamellate I'ostrum of Micippa and Para- 

 micippa is reduced to a single vertically deflexed spine, the prse- 

 ocular spines are enormously developed, and constitute the appa- 

 rent rostrum ; the anterior part only of the upper wall of the 

 orbit is developed, the posterior part, which, is complete in Mi- 

 cippa, being represented only by two or three spines : hence the 

 carapace behind the eyes appears constricted ; the basal antennal 

 joint, moreover, is narrower and elongated, Criocarcinus occupies 

 an intermediate position between Micippa and Picrocerus. 



§ Orhits very incomplete, tlie anterior portion partially surrounding 

 the eye-pedimcle, and usually of the form of a tube open below, the 

 posterior portion often represented only by one or two spines. 



Criocabcinus, "^.-JEdivards. (Plate XIII. fig, 3.) Orbits 

 tubular, open below ; prseocular spines small, Eostrum lamellate 

 at base, and terminating in two divergent spines. Legs of mode- 

 rate length. Type Criocarcinus superciliosus (Herbst). 



PiCROCEETJS, Alphonse Milne-Edwards. Orbits tubular, open 

 below. Eostrum rudimentary, composed of a single vertically 

 deflexed spine, Prseocular spines enormously developed, hori- 

 zontal, and slightly divergent ; constituting the apparent rostrum. 

 Legs long and slender. Type Picroeerus anyiatus, A. M.- 

 Edwards. 



PsEUDOMicippE, Heller. Orbits not tubular, covering the eye- 

 peduncles above, not defined below, with a hiatus above. Nos- 

 trum obliquely deflexed, composed of two divergent spines, Prse- 

 ocular spines small. Legs of moderate length. Type Pseudo- 

 micippe nodosa, Heller. 



Establishing the transition to Tyche and its allies. 



§§ Orbits of a narroio oval form, toell defined; basal antennal joint 

 micch enlarged. 



Micippa, Leach. (Plate XIII. figs. 1,2.) Eostrum nearly vei-ti- 

 cally deflexed. Anterior legs in male with the palm elongated 

 and rather slender ; fingers meeting along their inner edges when 

 closed. Type Ilicippa cristata (Linn.). 



