37i 



jS mm. long, finally, the front presents again another form : the lateral emarginations are 

 larger, so that the median part of the front appears less broad than usually and it is also 

 emarginate in the middle. In the specimen from Stat. 2S5, only 9 mm. long, the median carina 

 between the eyes is rather prominent. 



I will still add that in the three posterior legs the ischium is armed with a movable 

 spine, inserted on a concavity of the lower border. 



The largest ova-bearing specimens from Stat. 213, that are contained in the tubes of 

 Oscillariae, are 50111111. long; the females bear, however, already eggs at a much younger age: 

 so e. g. the egg-bearing female from Stat. 37 which is 21 mm. long and that from Stat. 131, 

 the length of which is only 15 mm.! The eggs are globular; those of the large females from 

 Stat. 213 are 0,75 mm. broad, whereas the eggs, few in number, of the small specimen from 

 Stat. 131 show a diameter of 0,62 mm. 



General distribution: New Holland (H. Milne-Edwards) ; Samoa Islands ( A. Milne- 

 Edwards, Ortmann); Tahiti (Heller); Liu-kiu-islands (Ortmann); Celebes (de Man); Amboina 

 (de Max, Ortmann); Ternate (de Man); Java Sea (de Man); Atjeh (de Man); Mauritius (Richters). 



III c. Insignis subgroup. 



f28. Alpheus bidens (Oliv.). 



Alpkeus bidens (Olivier) H. Milne-Edwards, in: Hist. Nat. Crustacés. II, 1837, P- 353' PI- 2 4> 



fig. 11 and 12. 

 Alpheus tridentatus L. Zehntner, Crustacés de 1 'Archipel Malais. Genève 1894, p. 204, PI. 



VIII, fig. 24. 

 Confer: H. Coutière, Les Alphéidae. Paris, 1S99, figs. 57 and 274. 



Stat. 131. July 24/25. Anchorage off Beo, Karakelang-islands. Reef. 7 specimens, among which 



1 male and 2 egg-bearing females. 

 Stat. 133. July 25/27. Anchorage off Lirung, Salibabu-island. Reef. 1 male. 

 Stat. 154. August 14. o°7'.2 N., I30°25'.5E. Bougainville Strait. S^ m. Grey muddy sand, 



shells and Lithothamnion. 1 female without eggs. 

 Stat. 240. November 22 till December 1. Banda-anchorage. From 9 — 45 m. Black sand, coral. 



Lithothamnion-bank in 18 — 36 m. 2 specimens, one of which is egg-bearing. 

 Stat. 282. January 15/17. 8°25'.2S., i27°i8'.4E. Anchorage between Nusa Besi and the N.E.- 



point of Timor. 27 — 54 m. Sand, coral and Lithothamnion. 1 female without eggs. 



H. Milne-Edwards and Coutière are, as far as I know, the only authors that have 

 observed this rare species, though it must be remarked that Zehntner's A. tridentatus is 

 identical with A. bidens, as was already suggested by Coutière (Buil. Muséum Paris 1897, 

 N° 7, p. 303) and as I was able to verify by the examination of both specimens of Zehntner, 

 kindly sent me by the Direction of the Museum at Geneva. Dr. Zehntner's description proved 

 to be not quite exact in a few particulars. In both specimens the carpocerite reaches only to 

 the 2 nd third part of 3 rd antennular article. In the female the i st article of the right antennular 

 pecluncle bears two spines, as in the specimens collected by the "Siboga"; that of the left 

 peduncle bears only one and this is also the case with the two peduncles of the younger 

 individual. The two fïrst carpal segments of the second legs, finally, are not of equal length, but, 



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