344 



on the upper border, but also the two on the outer resp. the inner surface, that are directed 

 from the articulation of the fingers almost to the middle of the palm, are quite conspicuous 

 and the outer surface of the immobile finger is deeply concave. The inner margin of ischium 

 and merus of the larger cheliped is finely denticulate. 



Remarks. Of the other species of the Macrochirus group A. socialis Heller from 

 New South Wales is perhaps the most closely related. In this species, however, the lateral 

 margins of the rostrum bear no hairs, the orbits present a small spine anteriorly and the basal 

 spine of the outer antennae extends almost to the end of 2 nd antennular article (though in 

 Fig. i of Plate X of the "Novara-Reise" it appears much shorter, not longer than i st article). 



General distribution: Mauritius (Richters) ; Dar-es-Salaam (Ortmann) ; Madagascar 

 (Coutière); Maledives (Coutière); Ternate (de Man); Tahiti (Ortmann); Rotuma (Borradaile) ; 

 Fernando-Veloso (Coutière); Congo (Coutière); Gulf of California (Coutière). 



III. Crinitus group. 

 III a. Obcso-manus subgroup. 



10. Alpheus microstylus (Sp. Bate). 



Betaeus microstylus C. Spence Bate, Report Challenger Macrura, 1888, p. 566, PI. Cl, fig. 6. 

 Alpheus microstylus H. Coutière, Alpheidae Mald. and Laccad. Archip. 1905, p. 884, PI. 



LXXVI, Fig. 23. 

 Alpheus obesomanus J. G. de Man, in: Archiv f. Naturg. 53. Jahrg. 1888, p. 520 and in: 



Abhandl. Senckenb. Naturf. Gesells. XXV, 1902, p. S67 — 869. 

 Confer: H. Coutière, Les "Alpheidae", 1899, p. 223, Fig. 270 — 272. 



Stat. 125. July 18/19. Anchorage off Sawan, Siau-island. Reef. 1 male and 1 egg-bearing 



female. 

 Stat. 144. August 7/9. Anchorage north of Salomakieë-(Damar)-island. Reef. 1 young male. 



The male from Pulo Edam (Bay of Batavia), described by me (1. c.) in 18S8 and in 

 1902 under the name of A. obesomanus Dana, is lying before me and proves to belong to 

 A. microstylus (Sp. Bate). 



The male and the female from Stat. 125 are respectively 18,5 mm. and 20 mm. long, 

 this species attains, however, a length of 25 mm. In all the specimens the rostrum is developed. 

 In the male from Stat. 125 the acute rostrum distinctly reaches beyond the orbital margins 

 and measures about one-fourth the visible part of the i st antennular article. The 2 nd article, 

 0,9 mm. long and 0,33 mm. thick, appears slightly more than one and a half as long as the 

 visible part (0,56 mm.) of the i st and almost 3-times as long as thick; 3 rd article two-thirds 

 of the 2 nd and a little longer than the i st . Stylocerite acute, pointed, reaching to the distal 

 3 rd part of i st article. The scaphocerite which is cleft to the middle and the lamina of which 

 is fringed with long, feathered hairs, appears just as long as the carpocerite but extends a little 

 beyond the far end of the antennular peduncle; the scaphocerite is just 3-times as long as 

 broad in the middle. 



The larger chela closely resembles the accurate figures 270 and 271 in Coutière's work 



