516 



also tliink 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 Estremadui'a ; var. N. 

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



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

 Sowerb/s Conch. Ulust., f. 47 ; var. f. 156. N. serratilineata, 

 Ziegler. 



N. testa N. Jluviat'di simih, sed anfractu ultimo subquadiato, 

 lineis angulatis longitudinahter picta. 



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

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

 N.fiuviatilis, with some forms of wliich, however, it is in close 

 affijiity. 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. Banubiensi simili, sed ultimo anfractu superne 

 carinato. 



The angularity of outline observed in the typical variety of 

 N. TJanubiensis 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. lU. f. 2. 



N. testa crassa, transverse ovali, striata, lineis nigris reticulatii ; 

 spii'a brevi ; aperturd alba, magna ; labio externo crasso ; labio 

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

 culo nigro. 



A much more soKd shell than N.fiuviatilis, &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 hp is narrow, arcuated, with blmit teeth. The opercu- 

 lum black. 



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

 Cimiing. 



