Pi^opsrrr oMiB!iMrf ^,^^ fisheries 



PART II 

 Family ALPHEIDAE 



It is especially to the important investigations of Professor Coutiere that science is 

 indebted for the fact that our knowledge of the Family Alphcidae has increased to such a great 

 extent, not only as regards the morphology and the biology of these interesting animals, but 

 also in view of the considerable number of new genera, new species and new varieties with 

 which he has made us acquainted. Coutiere also first called attention to the great importance 

 of the relative measurements of the thoracic appendages and of the telson as specific characters, 

 characters that previously had been overlooked by the carcinologists and it was just by means 

 of these new characters, that often specimens of small size of Alpheus or Synalpheiis proved 

 to belong to species that were still unknown, while formerly such specimens usually would be 

 regarded as juvenile forms or at most as varieties. 



At present not less than 19 genera are included in this family, one of which, however, 

 Raciliits Paulson, is regarded by Coutiere as doubtful, while the genus Parathanas Sp. Bate 

 has been created for specimens that apparently were still in a larval stage. The genus Aretopsis 

 is the only new one, discovered by this expedition. Excepting the old genus Alpheus and the 

 genus Sytialphejis^ that previously was united with the former, all these genera are represented 

 by few species and nine of them even by one species only. The genera Alpheus^ Synalphciis^ 

 Ogyris^ Automate^ Alpheopsis, Betacns, Jousseauiiica and ^itJia^ias are distributed not only 

 over the Indopacific region, but occur also in the Atlantic or on the coasts of America, the 

 Mediterranean or the Black Sea and Alpheopsis Haitgi Cout. inhabits a freshwater lake of 

 the French Congo at 200 kil. from the sea. The other genera of this family are confined to 

 the Indopacific region. While all the first mentioned genera were collected by the "Siboga", 

 of the latter only Arete and Aretopsis have been observed. 



As regards the distribution of the other genera, we know that Athanopsis Cout., 

 Pterocaris Heller, Parabetaeus Cout., Amphibctaeiis Cout. and Racilius Paulson have up to the 

 present time only been observed in the Red Sea or at Djibouti ; the remarkable genus CJieirothrix 

 that was discovered by the "Challenger", occurs at Cape York, the genus Alpheinus Borr. at 

 the Loyalty Islands and Aletabetaeus, finally, is still only known from the island of Funafuti. 

 The three last named may perhaps once prove to exist also in the East Indian Archipelago, 

 like also the two species of Parathanas Sp. Bate, that occur at the Philippine Islands. 



SIllOGA-EXPEDITIE XXXIX a'. 



18 



