299 



figure 15c of the original description; the dorsal hook, longer than the other and almost as 

 thick at its base, is curved and regularly tapers to the extremity ; the ventral hook has a 

 stouter form and, as in Syu. neptunus, its anterior margin runs like a S. The proportion between 

 the length of the merus and that of the propodus is 1,47, according to Coutière 1.6. 



With regard to the specimen, long 8 mm., from Stat. 282 the following must be observed. 

 The median antennular article is a little shorter than in the preceding specimen, being a little less 

 than half as long as the visible part of the first and the third is one and a half as long as 

 the second; the stylocerite of the left peduncle extends just beyond the first article, but that of 

 the right is as in the type. The terminal spine of the scaphocerite, though shorter than the 

 carpocerite, much surpasses the antennular peduncle and the scale reaches, like in the preceding 

 female, to the 2 nd third part of the third article. Frontal spines as in the preceding female. 

 The relative dimensions of the third pair of legs are: merus 2,52; carpus 1 ; propodus 1,77; 

 the merus is 4-times, the propodus 5,4-times longer than wide, appearing in this younger 

 specimen a little more slender than in the older one and the proportion between the length 

 of the merus and of the propodus is 1,42. The propodus bears six spinules and the dactylus 

 measures a little more than one-sixth of it. 



General distribution: Maldive and Laccadive Archipelagoes (Coutière) ; Pescadores 

 (Coutière). 



Alpheus Fabr. 



The genus Alpheus Fabr. is represented in this collection by no less than 54 species 

 and 8 varieties, of which 20 species and all the varieties proved to be new to science ; the 

 varieties all belong to known species. Moreover 3 species and 2 varieties were collected, that 

 are left unnamed, while also a new variety is described, which was not taken by the "Siboga". 

 A rich harvest indeed, a large contribution to the knowledge of this interesting genus, especially 

 when we take in consideration that the old genus Alpheus Fabr. has been some time ago 

 discharged of many species that are at present included in the genus Synalpkeus. The total 

 number of indopacific species of Alpheus therefore now amounts to 124, besides 4 that are 

 unnamed, while at present 19 varieties are known, 2 of which are still unbaptized. 



The 34 already known species, obtained by the "Siboga", constitute about one-third of 

 the total number of indopacific species, with which we were up to the present acquainted. Of 

 these 34 species 15, i. e. 44°/ i are widely-ranging forms, distributed throughout the whole 

 Indopacific. These species are the following : 



A. collumianus Stimps. 

 A. ventrosus H. M.-Edw. 

 A. macrochirus Richt. 

 A. Alcyonc de Man. 

 A. spongiaruiu Cout. 

 A. pachychirus Stimps. 

 A. frontalis H. M.-Edw. 

 A. Lutini Cout. 



A. insignis Heller. 

 A. gracilipcs Stimps. 

 A. Mi er si Cout. 

 A. Audouini Cout. 

 A. strenuus Dana. 

 A. pacificus Dana. 

 A. parvi-rostris Dana. 



167 



