EURYSTHEUS. 353 



A MPHIPODA . OA MMARIDES. 



NATATOEIA. 



Genus EURYSTHEUS. 



Eurystheus. SPENCE BATE, Rep. Brit. Assoc. 1855, p. 58. 



Ann. Nat. Hist. 2 set. xix. p. 143. Cat. 



Amph. Crust. Brit. Mus. p. 196. WHITE, 



Pop. Hist. Brit. Crust, p. 181. 

 Gammarus (Division + + a). LILJEBORG, Ofvers. af Kongl. Vet. Akad. 



Forhandl. 1854, p. 455. 



Generic character. Pereion and pleon of equal length. 

 Antennae subequal, long, and slender ; superior pair having 

 a secondary appendage. Gnathopoda subchelate; second pair 

 larger than the first. Posterior pair of pleopoda biramous ; 

 rami equal. Telson cylindrical. 



THE animals belonging to this genus have the body 

 very long, being quite half the length of the entire 

 animal. The antennae are long, slender, and sub-equal. 

 The superior are furnished with a secondary appendage. 

 The inferior originate posteriorly to the superior. The 

 mandibles are furnished with an appendage. The first 

 two pairs of legs are subchelate ; the second pair are larger 

 than the first, althougb not of great size. The walking 

 legs are long and slender, increasing in length posteriorly. 

 The caudal appendages are biramous; those of- the 

 posterior pair are not foliaceous. The terminal caudal 

 appendage is developed in the form of a small segment, 

 and probably the prima via debouches at its extremity. 



This genus may be distinguished from Mcera by the 

 form of the head and the character of the middle tail- 

 piece. 



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