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ANOMURA. 

 Tribe GALATHEIDEA. 



The three famihes having representatives in Irish waters 

 may be separated as follows : — 



A. — Posterior half of abdomen bent under 

 the first, but telson not tucked under last 

 segment ; telson broad, made up of separate 

 plates suggestive of a tergum and pair of 

 modified appendages ; antennal peduncle four- 

 jointed ; no acicle ; arthrobranchs normally 

 placed, .. ,. .. Galatheidae, Dana. 



B. — Abdomen bent as in Galatheidae, but 

 in addition the telson and uropods are tucked 

 under the last abdominal segment ; telson 

 narrow, weak, and transversely fissured ; 

 antennal peduncle five -jointed ; second joint 

 usually with an acicle ; arthrobranchs placed 

 on side of thorax, . . Uroptychidae, Henderson. 



C. — Cephalothorax very broad, almost 

 circular in outline ; abdomen bent and closely- 

 pressed against sternum as in Brachyura ; 

 third maxillipedes have ischium much 

 flattened, and merus with broad internal 

 lobe ; in the male a single pair of pleopods 

 present, on the second segment ; antennal 

 peduncle four -jointed ; no acicle ; arthro- 

 branchs normally placed, Porcellanidae, Henderson. 



Family UROPTYCHIDAE. 



Chirostylidae, Ortmann, 1892. Diptycinae, Milne-Edwards 

 and Bouvier, 1900. Uroptychidae, Alcock, 1901. 



The two genera included in the family may be separated as 

 follows : — 



Rostrum spiniform ; lateral margins of cara- 

 pace very obscure ; no acicle on antennae ; 

 chelipeds often more than five times length 

 of carapace and abdomen ; walking legs very 

 long, .. .. .. .. Gastroptychus. 



Rostrum flat and triangular ; lateral margins 

 of carapace well defined; well developed 

 triangular acicle ; chelipeds long ; walking 

 legs moderately long, . . . . Uroptychus, 



