CLASSIFICATION OF THE :MAT0ID CRUSTACEA. 



G57 



Avitli a spine at its aiitero-external angle, wliicli projects forward. 

 Anterior margin of buccal cavity straight, or nearly so. Merus 

 joint of outer maxillipedes dilated at its distal margin, rounded 

 and entire, without any notch for the insertion of the next joint. 

 Type Acantliophrys cristimanus, A. Milne-Edwards. 



I propose to restrict this genus to species characterized by the 

 entire merus joint of the outer maxillipedes, as there appears to 

 be no other certain distinction between it and Paramithrax, and 

 accordingly cite A. cristimanus as the type, because (if the figure 

 be correct) it presents this peculiarity. Two species of the genus 

 are in the British-Museum collection. 



tt Orbits small, ivith a lateral aspect; orhital margin not pro^ 

 minent, ivith a hiatus above and beloio (rarely in Pisa there are 

 two hiatus above). 



Pisa, Leach. (Plate XII. figs. 9, 10.) Carapace triangular, 

 rounded behind. Prseocular spine usually large. Spines of ros- 

 trum long, parallel, or in contact, to near their extremities. Epi- 

 stome transverse, rather narrow. Basal joint of antennae much 

 enlarged, and terminating at its distal extremity in one or two 

 spines or tubercles. 



Subgenus 1. Pisa, Leach (Blastus, Leach). Anterior legs in 

 the male with the palm dilated ; fingers curved, and meeting only 

 at the ends. Carapace ovate-triangular. Type Fisa tetraodon 

 (Pennant). 



Subgenus 2. Arctopsis, Lamarclc. Carapace subtriangular. 

 Anterior legs in the male with the palms elongated and rather 

 slender ; fingers straight, and meeting along their inner edges. 

 Type Arctopsis lanata^ Lamarck. 



*PisoiDES, Milne-Edwards 'Sf Lucas. Carapace subtriangular. 

 Spines of rostrum short, subparallel. No prseocular spine. Epi- 

 stome very narrow, nearly linear. Basal antennal joint with a 

 tubercle at its distal end. Type Pisoides Edwardsii (Bell). 



NoTOLOPAS, Siimpson. Carapace with the back flattened, and 

 bounded ^posteriorly by a broad concave lamella. Eostrum with 

 the spines divaricate. A prseocular spine. Basal joint of an- 

 tennse with a lobe at its distal end. Type JVotolopas lamellatusj 

 Stimpson. 



49* 



