CLASSIFICATION OF THE MATOID CRUSTACEA. 



GGl 



Notwithstanding the great dissimilarit}^ of Micippa and Ficro- 

 ceriis, which stand at opposite extremes of the scries, a rcguhir 

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

 Picrocerus the broad and lamcHate rostrum of Micippa and Para- 

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

 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. 



§ Orbits very incomplete^ the anterior portion partially surrounding 

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

 posterior portion often represented only by one or tivo spines. 



CmocAECiNus, M.-Udtvards. (Plate XIII. fig. 3.) Orbits 

 tubular, open below ; praeocular spines small. Eostrum lamellate 

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

 rate length. Type Criocarcinus superciliosus (Herbst). 



PiCEOCEEUS, Alphonse Milne-Edwards. Orbits tubular, open 

 below. Eostrum rudimentary, composed of a single vertically 

 deflexed spine. Praeocular spines enormously developed, hori- 

 zontal, and slightly divergent ; constituting the apparent rostrum. 

 Legs long and slender. Type Picrocerus armatus, A. M.- 

 Edwards. 



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

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

 trum obliquely deflexed, comp)Osed of two divergent spines. Prae- 

 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, well defined; basal antennal joint 

 much enlarged. 



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

 cally deflexed. Anterior legs in male with the palm elongated 

 and rather slender ; fingers meeting along their inner edges when 

 closed. Type Micippa ci'istata (Linn.). 



