CLASSIFICATIOK OF THE MAIOID CRUSTACEA. 



GG3 



§§ Nostrum composed of two distinct spines, 

 * Basal joint ofantennce tvithotit a spine at its distal extremity. 



ScTRA, Dana. PrcTocular spine present. Spines of rostrum 

 lamellate at base, acute at distal end. Easal joint of antenna) 

 narrow. Anterior legs ratlier long, palm carinated. Ambula- 

 tory legs not compressed. Type Scyra acutifions, Dana. 



*Ptria, Dana. Pra30cular spine absent. Spines of rostrum 

 lamellate. Anterior legs slender. Ambulatory legs much com- 

 pressed. Type Pyria piibescens^ Dana. 



Nothing is said respecting the orbits and basal antennal joint ; 

 if the orbits are incomplete, this genus would probably be placed 

 near Chionoscetes. 



LissA, Leach. Carapace very convex. Praeocular spine pre- 

 sent. Spines of rostrum flattened, contiguous, and produced at 

 their extremities into a lateral lobe. Basal joint of antennae much 

 enlarged. Anterior legs with the palm compressed but not cari- 

 nated. Ambulatory legs of moderate length. Type Lissa cJii- 

 ragra (Fabr.). 



*Eachinia, a. Milne-Edwards. Praeocular spine present. 

 Spines of rostrum slender and divergent. Anterior legs with 

 tlie palm compressed but not carinated. Ambulatory legs very 

 slender. Type Bacliinia gracilipes, A. Milne-Edwards. 



The description of this genus is taken from the figure in the 

 ' Mission Scient. Mexique, Crustaces Podophthalmaires,' pi. xviii. 

 fig. 1. The species is noticed, but not described, in a footnote on 

 p. 86. Of this fine work, wLich contains descriptions and figures 

 of many new genera and species, only a portion, referring to the 

 Crustacea Xiphosura and a part of the Oxyrhyncha, has yet ap- 

 peared (5me partie, livraisons 1-3. Paris, 4to, 1873 & 1875). 



*Leptopisa, Stimpson. Carapace narrow, with perpendicular 

 sides. Spines of rostrum very slender and contiguous. Anterior 

 legs in the male large ; fingers widely gaping. Ambulatory legs 

 long and slender. Type Leptopisa setirostris, Stimpson. 



*SpHEXOCARCiiTrs, A. 3I.-Edivards. Carapace triangular, 

 liostrum elongated, its spines contiguous to within a very short 

 distance of their extremities, which are acute. Anterior legs 

 small. Ambulatory legs of moderate length. Type Bplienocarci- 

 nus corrosus, A. M. -Edwards. 



