341 



This species is most closely related to A. splendidus Cout. from Djibouti (Bull. Museum 

 Paris, 1897, N" 6, p. 235), to A. gracilis Heller from the Red Sea, to its variety Alhiatidi 

 Cout. from Hulule Male Atoll and to A. aglaopheniae Borr. from New Guinea. Length of the 

 adult specimen from Pulu Jedan 18 mm., carapace 6,4 mm. long, smooth and glabrous. The 

 rostrum is acute, pointed, narrow, 3-times as long as broad at its base and reaches to the end 

 of the first antennular article ; whereas the lower margin of the rostrum is slightly ascending, 

 the obtuse upper border is as slightly directed downward. Rostral carina not compressed, some- 

 what widening backward, obtuse and extending almost to the middle of the carapace (the 

 rostrum included) ; in a lateral view the carina appears slightly directed downward, not fully 

 concealed by the orbital hoods from which it is separated by moderately broad and moderately 

 deep grooves. The orbits are armed anteriorly with an acute spine, which is slightly 

 directed inward and much shorter than the rostrum, reaching to the 2°'^ third part of its 

 length. In Heller's type specimen of A. gracilis^ that I had the opportunity to study (p. 337), 

 the orbital spines reach about to the middle of the rostrum. At either side, between the rostrum 

 and the orbital spines, the frontal margin shows, in A. facet us, an arcuate prominence; 

 these prominences, however, hardly project bej-ond the orbital hoods. 



Telson 2,3 mm. long, one and a half as long as broad, while the slightly arcuate, posterior 

 margin measures one-third its length; upper surface smooth, glabrous, with a broad, shallow 

 groove that runs from the base to the posterior margin and with 2 pairs of rather large 

 spinules, the anterior pair situated nearly in the middle. In Heller's type of A. gracilis the 

 telson shows nearly the same characters, but the anterior pair of spinules are situated before 

 the middle and the telson appears a little less broad (p. 338). Uropods much longer than the 

 telson, endopod oval, movable spine, near the spiniform postero-lateral angle of the outer 

 uropod, black; like in A. gracilis, of the two spines of the basal joint the inner is much 

 smaller than the outer. 



Second joint of antennular peduncle one and three-fourths as long as thick, a little 

 shorter than the visible part of the first, measured from the base of the rostrum, third article 

 one-sixth shorter than second ; the stylocerite is slender and terminates in a spine that almost 

 reaches to the middle of the second joint. In A. gracilis the antennular peduncle and the 

 stylocerite almost resemble those of this species. 



The spine of the basicerite reaches nearly as far as the first joint of the antennular 

 peduncle and it is broad at its base; the carpocerite is robust and reaches beyond the tip of 

 the antennular peduncle by half the length of the third article. The scaphocerite which is as 

 long as the carpocerite and the outer margin of which is almost straight, is 2, 5 -times as long 

 as broad and the terminal spine extends beyond the tip of the scale by one-third of its length, 

 while the scale is just as long as the antennular peduncle. 



Penultimate joint of external maxillipeds twice as long as thick, terminal joint twice as 

 long as the penultimate and 5-times as long as broad, narrowing towards the distal extremity. 

 Merus of the large cheliped half as wide at distal end as it is long; the upper margin 

 terminates in an acuminate spine, which is curved inward, the infero-external margin is straight, 

 entire, the infero-internal is armed with 2 or 3 small spinules while there is an acute tooth at 



209 



SIBOGA-EXPEDITIE XXXIX (7 '. 44 



