è 3 Lateral (extra-corneal) teeth wanting. 



Cj Dactyli of three posterior legs biunguiculate. 



d 1 Orbital hoods rounded anteriorly, rostrum triangular, flattened 

 above, with the lateral margins setose. Larger chelioed with 



the upper margin of the merus obtuse at apex macrochirus Richt. 



d, Orbital hoods acute in front, rostrum continued backward as a 

 short keel on the carapace. Larger cheliped with the upper 



margin of the merus terminating in a large spine .... aglaopheniae Borr. 

 (L. A. BORRADAILE, in: A. Willey's Zool. Results, Part IV, 1S99, p.417, Fig. 13a — 13/"). 



c 2 Dactyli of three posterior legs simple. Orbital hoods hemispherical, 



convex. Rostral carina prominent, reaching to just behind the 



orbital hoods. Larger chela 3,5-times as long as high, with the 



fingers extraordinarily short and the dactylus hammer-shaped . idiocheles Cout. 



(H. CüUTIÈre, Alpheidae Mald. and Laccad. Archip. 1905, p. 883, PI. LXXV, fig. 21). 



In his paper on the Alpheidae of the Mald. and Laccad. Archip. 1905, p. 882, Prof. 

 Coutière makes mention with a few words of a variety Alluaudi of A. gracilis Heller, which 

 only should differ from the type by the dactyli of the three posterior legs being simple. It is 

 not included in this key, because in Coutière's specimens the first pair of legs were wanting. 



Obeso-manits subgroup. 



a Y Merus of 3 ,d legs armed with an acute tooth at distal extremity of 

 posterior margin. 

 ó 1 Dactyli of three posterior legs simple. 



c l Terminal spine of scaphocerite reaching at least to the extremity 



of 2 nd antennular article, this article at most 3-times as long as 



thick ; 2 nd carpal article of 2" d legs more than 3-times as long 



as 1 st , rarely only twice as long or still less. 



d^ Fingers of the small chela of the male much shorter than the 



palm, the proportion between the length of the chela and that 



of the fingers more than 3. 



l\ Larger chela not furrowed at all ; 2 nd carpal article 4-times as 



long as 2 nd ; fingers of smaller chela one-fourth the whole 



length obeso-manus Dana 



(J. D. Dana, U. S. Explor. Exp. Crust. p. 547, PI. 34, fig. 7). 



£ 2 Larger chela distinctly furrowed; 2 nd carpal article 3,3 — 3,4- 

 times as long as 2 nd ; proportion between the length of the 



smaller chela of the male and that of the fingers 3,15. . microstylus (Sp. Bate) 

 d„ Fingers of the small chela of the male little shorter than the 

 palm, the proportion between the length of the chela and that 

 of the fingers less than 3. 



180 



