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Key to the indopacific species of the genus Alpheopsis Cout. 



a y Carpus of second legs triarticulate. No extra-corneal spines. Ptery- 

 gostomian angle terminating in an acute triangular point. Legs of 



first pair unknown idiocarptis Cout. 



(H. COUTIÈRE, in: Buil. Soc. Philom. Paris, 1908, p. 4). 

 a i Carpus of second legs five-articulate. 



b x Dactyli of three posterior legs biunguiculate. No extra-corneal spines. 



Legs of the first pair unknown fissipes Cout. 



(H. COUTIÈRE, in: Buil. Soc. Philom. Paris, 1908, p. 3). 

 b„ Dactyli of three posterior legs simple. 



c l Posterior margin of the telson straight or a' little convex. 

 d x Chelae of first pair entire and smooth. 

 e l Front without extra-corneal spines. 



f x Pterygostomian angle of the carapace rounded. 



g x Rostrum acute aeqnalis Cout. 



(H. COUTIÈRE, in: Buil. Mus. Paris, 1896, N° 8, p. 380). 



g„ Rostrum truncate aeqnalis Cout., var. trtmcatus Cout. 



(H. COUTIÈRE, Alph. Mald. and Lacc. Archip. 1905, p. 868, Fig. 139). 



f„ Pterygostomian angle terminating in a small acute tooth. 

 Rostrum acute. Antennular peduncle with the second article 

 a little wider than long. Chelipeds unequal, palm of the 



large chela one-fourth longer than the fingers .... consobrinus de Man 

 e„ Front trispinose. Pterygostomian angle with a small, acute 

 tooth or spine. Chelae of the first pair in the female with 

 the palm slightly shorter than the fingers. Three posterior 



legs slender, merus of third pair 8-times as long as wide . Clialciope de Man 



d„ Chelae of first pair more or less grooved, with the dactylus 



lunulate. Front trispinose. 



e 1 Chelae of first pair entirely inverted, equal, dactylus quite 



inferior. No transverse groove behind the articulation of the 



dactylus ; cutting-edge of the dactylus with a slight promi- 



nence, fitting, as in the genus Amphibetaeus, into a deep 



groove of the immobile finger Sibogae de Man 



e 2 Chelae of first pair unequal, dactylus at most in a horizontal 

 plane. A deep transverse groove behind the articulation of 

 the dactylus, the dactylus with one tooth, the immobile 



finger with two trispinosus Stimps. 



(W. STIMPSON, in: Proc. Acad. Nat. Scienc. Philadelphia, 1860, p. 32). 



C 2 Telson terminating, like in the genus Parabctaeus, in a large, acute 

 tooth, that measures one-ninth the whole length of the telson. No 

 extra-corneal teeth. Rostrum acute. Legs of the first pair unknown. Euryone de Man 



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