Mr. C. Spence Bate on British Edriophthalmous Crustacea. 135 



XII. — A Synopsis of the British Edriophthalmous Crustacea. 

 By C. Spence Bate, F.L.S. &c. — Part I. Amphipoda*. 



Class CRUSTACEA. 



Legion II. Edriophthalma. 



Order I. AMPHIPODA. 



Group A. NORMALIA. 



Division I. Gammarina. 



Subdivision I. VAGANTIA. 

 Do not construct abodes to dwell in. 



Tribe I. Saltatoria. 

 Mode of progression out of the water is by leaps. 



Family I. Orchestidse. 

 The upper antenna shorter than the lower. The coxse well 

 developed ; the posterior pleopoda short and robust, the last being 

 single. 



Genus 1. ORCHESTIAf. 



Upper antenna rudimentary ; the lower with the basal joints 

 absorbed within the facial wall of the cephalic segment. Olfactory 

 spine absent. The second pair of feet subcheliform. 



Subgenus 1. Talitrus, Latr., Bosc, Leach. 

 First pair of feet simple in both sexes. 



1. T. Locusta, Latr. Second pair of feet feeble, terminating in 

 a subcheliform hand, and folded beneath the body; the 

 dactylos small, and articulating remote from the apex of 

 the propodos. The last pair of the posterior pleopoda 

 rudimentary. The telson obsolete. 

 Sandy shores all round Europe, at high-water mark. 



Subgenus 2. Talorchestia, Dana. 

 First pair of feet simple in female only. 



[Of this subgenus there is no British species known.] 



* The classification adopted in this Synopsis is the result of the united 

 labours of Mr. Westwood and the author ; it is based on the structure and 

 the habits of the animals as far as known. The characters given are only 

 those which more immediately strike the observer. Many of the terms 

 employed are new ; they are explained at the end of this paper. 



t The classification adopted in this genus is that given by Dana, and the 

 result of his discovery of the intermediate form of Talorchestia. 



