516 



also think that the others must be included, as the variations, even 

 among specimens of the same varieties and localities, are almost 

 infinite. 



The principal varieties, and var. N. Bmtica (Lamarck), are 

 Sicilian ; var. N. inquinata is found at Estremadura ; var. N. 

 lutesceus, at Cephalonia; and var. N. Moreleti, in Portugal. 



30. Neritina Danubiensis (p. cxiv. f. 155, 156), Sadler, 

 Sowerby's Conch. Illust., f. 47 ; var. f. 156. N. serratibneata, 

 Ziegler. 



N. testa N.fluviatili simili, sed anfractu ultimo subquadrato, 

 bneis angulatis longitudinaliter picta. 



The specimens vary, but there is a greater tendency to angula- 

 rity of outline, and the outer lip is not so much extended as in 

 N.fluviatilis, with some forms of which, however, it is in close 

 affinity. In the variety (f. 156) named N. serratilineata, Ziegler, 

 from the Lago di Como, Italy, the linear markings are beauti- 

 fully angulated, and in the original variety, from the Danube, 

 they are more straightened. 



31. Neritina carinata (pi. cxiv. f. 157, 158), Koch. 



N. testa N. Danubiensi simili, sed ultimo anfractu superne 

 carinato. 



The angularity of outline observed in the typical variety of 

 N. Damibiensis is increased in this species so as to form a keel on 

 the upper part of the whorl. The markings are in a longitu- 

 dinal direction, more or less angulated. The aperture tends to 

 yellow. 



32. Neritina reticulata (pi. cxi. f. 74), Sow. Pro. Zool. 

 Soc., 1832 ; Conch. 111. f. 2. 



N. testa crassa, transverse ovali, striata, bneis nigris reticulata ; 

 spira brevi; apertura alba, magna; labio externo crasso; labio 

 interno angusto, margine obtuse dentato, in medio arcuato. Oper- 

 cido nigro. 



A much more sobd shell than N.fluviatilis, &c, with the 

 mouth not so large in proportion to the body. The outside is 

 transversely striated, and marked with reticulated black lines. 

 The inner lip is narrow, arcuated, with blunt teeth. The opercu- 

 lum black. 



Lord Hood's Island, South Seas ; on sand, brackish water. 



Cuming. 



