108 ZOÖLOGISCHE MEDEDEELINGEN — DEEL V. 



Synalpheus hastilicrassus Cout., var. acanthitelsoniformis n. 



1 male collected July 9/11, 1899, by the Siboga Expedition at the 

 east side of Pajunga Island, Kwandang-bay, on the reef (Stat. 115). 



The pleopod of the 2nd pair bears neither an appendix masculina 

 nor a stylamblys and also in the other pleopods a stylamblys does not 

 occur: therefore this specimen is considered to be a male (H. Coutière, 

 Les „Alpheidae", 1899, p. 296). This specimen differs from the typical 

 species by the spiniform postero-lateral angles of the telson projecting 

 by half their length beyond the 'posterior margin, exactly as in Syn. 

 acanthitehonis Cout., furthermore by the longer terminal spinules of the 

 telson projecting by three-fourths of their length beyond the posterior 

 margin, measuring two-thirds the width of the latter. 



Length about 10 mm. 



Alpheus anchistus n. sp. '). 



Alpheus sp., J. GL de Man, Siboga Exp. Mon. 39a, Alpheidae, 1911, 

 p. 383, PL XIX, figs. 85— 85 b. 



1 male and 1 egg-bearing female collected by the Siboga Expedition 

 off Ambon at a depth of 54 m. 



The nearest related species are A. tenuicarpus, A. tenuipes and 

 A. rapacida, described in my work on the Siboga Alpheidae. The two 

 specimens belong to the same species as the male 2 ) from Stat. 51, de- 

 scribed by me (1. c.) as Alpheus sp. The two pairs of antennae agree 

 with the figure 85, but in both specimens the antennal peduncle is just 

 as long as the peduncle of the upper antennae. Merus of the small che- 

 liped of the female 5-times as long as broad, upper margin unarmed at 

 distal extremity, infero-external margin serrulate by about 25 serrula- 

 tions, infero-internal margin with 5 movable, aciculiform spinelets and 

 a small acute tooth at the distal end; palm 3,25-times as long as broad, 

 a little shorter than the fingers, proportion between their length like 13:16. 



Relative measurements of the 3 rd leg of the male : merus 2,2 ; carpus 1 ; 

 propodus 1,44; dactylus 0,75. Merus 7,7-times as long as broad, carpus 

 4-times as long as thick, propodus almost 10-times as long as broad in 

 the middle. Relative measurements of the 4th leg in the male : merus 1,9, 



1) 'tkyxtfrroc, = related, allied. 



2) The specimen from Stat. 51 was reexamined by me and proved to be a male, the 2nd 

 pleopod bearing a stylamblys and a setose appendix masculina. 



