389 



infero-external margin entire, not serrulate. (In two younger type specimens the infero-internal 

 margin carries 3 small spinelets). Larger chela twice as long as broad, in adult type specimens 

 two and a half times; the chela agrees with Fig. 279 of Coutiere's work of 1899, but the 

 lower margin runs distally a little upward and is not concave at the base of the immobile finger. 



In the right leg of the 2""^ pair the carpal segments are i mm., 0,6 mm., 0,32 mm., 

 0,34 mm. and 0,54 mm. long, while the second segment is little more than twice as long as 

 thick; chela 1,08 mm. long (palm 0,56mm., fingers 0,52 mm.). The left leg agrees with the 

 right e.xcept the fifth segment of the carpus that is as long as the second. (In one of the 

 adult type specimens from Djibouti the carpal segments are 1,3 mm., o,S mm., 0,32 mm., 0,34 mm. 

 and 0,68 mm. long, the second segment 0,35 mm. thick; chela 1,28 mm. long (palm 0,55 mm., 

 fingers 0,73 mm.)). These numbers show that the carpus has a stout form, that the second 

 segment is little more than half as long as the first, that the fifth is usually a little shorter 

 than the second and that the fingers are in the adult distinctly longer than the palm, in younger 

 specimens slightly shorter than it, whereas the chela is as long as the first segment. 



Ischium of the three following legs armed with a small movable spine. Merus of 3''^ pair 

 little more than 3-times as long as broad, unarmed; carpus 2,5-times as long as thick; propodus 

 one-third longer than the carpus, little more than 3-times as long as broad, straight, slightly 

 narrowing distally, with the posterior margin bearing 4 spines besides 2 at the distal extremity ; 

 dactylus half as long as the propodus, simple. 



Remarks. Alpheus socialis Heller differs i" by the triangular, otherwise shaped rostrum, 

 2° by the orbits that are armed with a spine, 3" by the second antennular article being twice 

 as long as the first, 4" by the spine on the basicerite being long, 5" by the upper border of 

 the larger chela being entire, 6" by the dactyli of the posterior legs presenting an accessory claw, etc. 



General distribution: Djibouti (Coutiere) ; Mascate (Coutiere). 



f 40. AlphetLs pzidcscetis de Man. 



J. G. DE Man, in: Notes from the Leyden Museum, Vol. XXX, 1898, p. 109. 



Stat. 43. April 4/5. Anchorage oft" Pulu Sarassa, Postilion-islands. Depth up to 30 m. Coral. 

 I young specimen. 



Stat. 60. April 27/28. Haingsisi, Samau-island. Timor. Lithothamnion in 3 m. and less, i male 

 of medium size and i younger specimen. 



Stat. 71. May 10 — June 7. Makassar. Depth up to 32 m. Mud, sand with mud, coral, i egg- 

 bearing female. 



Stat. jy. June 10. 3°27'S., ii7°36'E. Borneo-bank. 59 m. Fine, grey coralsand. i female 

 without eggs. 



Stat. 162. August 18. Between Loslos and Broken-islands, West coast of Salawatti. 18 m. 

 Coarse and fine sand, with clay and shells, i adult, mutilated female. 



Stat. 273. December 23/26. Anchorage off Pulu Jedan, East coast o'f Aru-islands. (Pearl-banks). 

 13 m. Sand and shells. I adult male and i ova-bearing female. 



A new species of small size of the Brevirostris group. The adult male from the 

 Aru-islands is 20,5 mm. long, the egg-bearing female from Makassar 18 mm.: these two will 

 be described as the types of this species. 



257 



SIBOGA-EXPEDITIE XXXI.Xa'. ■ 50 



