38s 



setose; dactylus slender, 8-times as long as thick, half as long as the carpus and measuring 

 almost two-fifths of the propodus. 



Ischium of 5''' legs unarmed. Merus, carpus and propodus of subequal length, the carpus 

 as much shorter than the merus as the latter is shorter than the propodus, the propodus being 

 about one-tenth longer than the carpus ; dactylus measuring a little more than one-third of the 

 propodus. 



Table of measurements. 



Proportion between length of telson and width of the posterior margin 



Proportion between the width at the base and that of the posterior margin 



Proportion between length of telson and the distance of the anterior pair of spinules from 



the posterior margin 



Proportion between the distances of botli pairs from the posterior margin 



N'^ I the larger specimen long 13 mm.; N° 2 the female long 11,5 mm. 



IV. Brevirostris group. 



37. Alpheus rapax Fabr. 



Alphciis rapax J. C. Fabricius, Supplementum Entomologiae Systematicae, 1798, p. 405. 

 Alpheus inalabariciis F. Hilgendorf in: Monatsb. Kgl. Akad. Wiss. Berhn, 1878, p. 832. 

 Alpheus brevirostris J. G. de Man, in: Journal Linnean Society, London, Vol. XXII, 1888, p. 261, 

 Alpheus rapax H. Coutiere, Les "Alpheidae", Morphologie externe et interne etc., Paris, 1899, 



p. 233, fig. 284. 

 Alpheus rapax J. G. de Man, in: Memoires Soc. Zoolog. France, 1909, p. 147, PI. VII, figs, i — 8. 



Stat. 234. November 19/20. Nalahia-bay, Nusa-Laut-island. 46 m. Bottom stony. 2 adult 

 specimens, one of which is egg-bearing. 



These two specimens have been fully described by me in a paper published in 1 909 

 (1. c.) on some species of the genus Alpheus appertaining to the Brevirostris group, in which 

 paper also the differences have been pointed out existing between A. rapax on one side and 

 A. brevier istat us de Haan, A. brevirostris (Oliv.) and A. distingjiendtis de Man on the other. 



General distribution: Zanzibar (Hilgendorf); Djibouti (Coutiere) ; Mergui Archipel- 

 ago (de Man). 



138. A/phens brevirostris (Oliv.) var. angustodigitus n. 



Confer: H. Milne-Edwards, Hist. Nat. Crust. II, 1837, p. 350 and J. G. DE Man, in: Mem. 

 Soc. Zoolog. de France, 1909, p. 153 — 160 (passim in texto). 



Balikpapan, east coast of Borneo, i adult male and i adult, egg-bearing female collected by 

 Mr. J. W. TiSSOT VAN Patot and preserved in the Zoological Museum of the University 

 of Amsterdam. 



Whereas the male is not injured at all, the female has lost all its legs excepting one 

 of the 2'"^ pair. In the cited paper several observations regarding A. brevirostris (Oliv.) were 

 pubHshed by me on Olivier's type specimen from New Holland, which courteously had been 



253 



