410 PROCEEDINGS OF THE ACADEMY OF [1894. 



Geographical distribution: Fresh- water of the West Indies and 

 the Cape Verde Islands. — Mexico (Wiegmann, Milne-Edwards, v. 

 Martens, Stimpson, Sharp) ; Nicaragua (Smith) ; Cuba (v. Martens); 

 Hayti (Kingsley) ; Jamaica (Newport); Dominica (Pocock); Mar- 

 tinique (Sharp); Tobago (Mus. Strassburg 18 ). — Cape Verde Islands: 

 San Nicolao (Newport); San Jago (Bate). 



7. Atya gabonensis Giebel, 1875. 



Atya gabonensis Giebel, Zeitscbr. f. d. gesammt. Naturwiss. (2), XI, 1875, 



p. 52. 

 Euatya sculp Ulis Kölbel, Sitz. Ber. Acad. Wiss. Wien, vol. 90, 1, 1884, p. 317, 



pi. 2, fig. 8, pi. 3. 

 Ayta scuiptata Ortmann, Zoolog. Jabrb., V, 1890, p. 465. 



Geographical distribution : Gaboon (Giebel); Orinoco (Kölbel). 



8. Atya (Evatya) crassa Smitb, 1871. 



Smitb, 2 and 3 Eep. Peabody Acad. Sei., 1871, p. 95. 



Kölbel, Sitzb. Acad. Wiss., Wien, vol. 90,1, 1884, p. 318, foot-note. 



Geographical distribution: Nicaragua (Smith); Mexico: Presidio 



(Kölbel). 



Doubtful Species. 



Atya poeyi Guérin, Crust, in Eamon de la Sagra, Hist, de File de Cuba, 1857, 

 p. 46, pi. 2, fig. 7.— Cuba. 



Caridina mexicana Saussure, Mem. Soe. Pbys. Hist. Nat. Geneve, 14, 2, 1858, p. 

 463, pi. 4, fig. 26.— Mexico. 



Atyoida glabra Kingsley, Proceed. Acad. Nat. Sei., Pbiladelpbia, 1878, p. 93. — 

 Nicaragua. 



Atya serrata Bate, Cballenger Macrur., 1888, p. 699, pi. 119, fig. 2. — Cape Verde 

 Isl. : San Jago. 



These species may be the young of A. scabra or may belong to 



Atyoida. 



Considerations concerning the geographical distribution of the 



Atyidce. 

 Some species of Atyidoe were formerly considered to be marine 

 animals; there is now no doubt that this family contains only fresh- 

 water forms. This family is probably one of the most primitive 

 groups of Decapoda living in fresh- water, having immigrated at an 

 early geological period. 



Only two species, Caridina ivycki and gracilirostris, are recorded 

 by Weber 19 as found in a few cases in brackish waters of Sumatra 



18 Tbis locality is not yet published : there is one adult male frornTobago in 

 the museum at Strassburg. 



19 Die Süsswassercrustaceen der ludischen Archipels. — Zoolog. Ergebn. 

 Eeise Niederl. Ost.-Indien., II, 1892, p. 542. 



