Crangon and Galathea. 57 



The characters of the carapace separate Crangon and Steiracrangon 

 from -3^geon and Cheraphilus, and the characters of the rostrum 

 from ^geon. Examination of the British species, of all sizes, 

 prove that these characters are constant at all stages of their per- 

 fect state. 



STJB-FAMILT, CEANGONIDiE. 



Carapace depressed ; rostrum short, not articulated ; eyes not concealed 

 beneath carapace ; external antenna3 unifilamentous, furnished with a broad 

 scale at their base ; internal anteunte dilated at base, peduncle short, bifilamen- 

 tous ; external maxillipeds subpediform, flattened. Chelipeds, five pairs ; 

 first pair subcheliform ; second didactyle ; third to fifth pairs simple acumi- 

 nate. Branchite, seven on each side ; antennse inserted nearly on same line. 

 Genera : Crangon, Cheraphilus, Mgeon. 



Genus Crangon. Rostrum triangular, shorter than the eyes. Carapace : 

 median gastric region armed with a single spiny tooth at most ; branchial re- 

 gions with a single tooth, not ridged ; antenna; ?is family ; abdomen smooth 

 above ; telson triangular, smooth above ; orbits circular, sparsely pubescent ; 

 first pair chelipeds Avell developed ; second pair as strong as fifth ; antenna! 

 scale large. Species : Cr. vulgaris, Franciscorum, rubropunctatus. Subgenus : 

 Steiracrangon ; abdominal somites carinated ; telson sulcated. Species : St. 

 projnnquns, nigricauda^ affi.nis^ Allmanni. 



Genus Cheraphilus (mihi), Pontophilus (Leach, not Eisso or De Haan). 

 Rostrum triangular, moderate ; carapace cariuate ; gastric region armed with 

 one or more carina ; branchial region multicarinated ; abdominal somites cari- 

 nated and sculptured ; telson sulcated above ; first pair chelipeds robust, mo- 

 derate in length ; second shorter than first : antennse as family ; antennal scale 

 short. Species : Ch. bispinosus, trispinosus, intermedius, bidentatus, angusti- 

 cauda, Pattersonii, spinosus, boreas, Capensis, nanus, munitus. 



Genus Jigeou. Rostrum truncate, or bifid; carapace : branchial and gastric 

 regions highly carinate ; abdominal somites toothed, carinated, and sculptured ; 

 telson generally sulcate; first pair chelipeds moderate, barely surpassing second 

 in length ; second pair slender ; orbits rounded, densely hairy ; antennas as 



