OF MERGUI AND ITS ARCHIPELAGO. 



165 



26. Neritina (Clithon) brevtspina, Lamarck, ffist. Wat. 

 Anim. s. Vert. ed. 1, vol. vi. p. 185, ed. 2, vol. viii. p. 572 ; Sowerby, 

 Tliesaur. Conch, vol. ii. pi. 110. figs. 45, 51, 52 ; Beeve, Conch. Icon. 

 vol. ix. Neritina, pi. vi. fig. 28 ; v. Martens, loc. cit. p. 156, pi. 17. 

 figs. 1-4. 



King Island Bay, rocks in fresh water. Widely distributed 

 from the Nicobar Islands to New Caledonia. 



Var. mutica (without spines), Sowerby, Thes. Conch, ii. pi. 110. 

 fig. 48 ; v. Martens, loc. cit. figs. 2, 3. 



Neritina subgranosa, Sowerby, Conchol. Illustr. no. 41, fig. 14 ; Thesaur. 

 Conch, ii. p. 524, pi. 110. fig. 35 ; Reeve, Conch. Icon. ix. Ner. pi. v. fig. 24. 



On rocks, freshwater, Sullivan and King Island, with the 

 preceding. 



27. Neritina (Clithon) ayellana, Becluz, Bevue zoologique, 

 1842, p. 76 ; Sowerby, Thesaur. Conch, ii. p. 527, pi. 109. figs. 9, 

 10 ; Beeve, Conch. Icon. ix. Ner. pi. xiv. fig. 64 ; v. Martens, 

 Monogr. Neritina, p. 174, pi. 18. figs. 5-9, & 11, 12. 



Sullivan Island, with N. auriculata and N. brevisjpina, var. 

 mutica. 



The coloration is somewhat variable, yellowish or reddish or 

 greenish, with scattered pale spots ; some specimens also with 

 interrupted dark bands. 



Borneo, Philippines, Formosa. 



Some other species of Neritina, see below nos. 56-59. 



28. Unio marginalis, Lamar ck, Hist. Nat. Anim. s. Vert. ; 

 Beeve, Conch. Icon. xvi. Unio, fig. 297 ; Conchol. Ind. pi. 43. 

 fig. 2. 



Rangoon. Bengal. 



29. Cvrena proxima, Prime, Annals of the Lyceum of Nat. 

 Hist, of New York, viii. 1864, p. 85, with woodcut. 



Sullivan Island, fresh water. Salang (Weber), Siam, 



C. SUBMARINE MOLLUSCA. 



The estuaries of the rivers and the mangrove-swamps nourish 

 a certain number of peculiar species of Mollusca, some of which 

 are air-breathing, others truly aquatic ; but all may be found at 

 the same spot and are quasi-intermediate between the freshwater 

 and truly marine fauna. 



