BY THE REV. J. B. TEGISON- WOODS, F.G.S., F.L.S., ETC. 115 



described by Eumpliius from specimens obtained by liim in the 

 Molliicas. 



JSferita alhicilla, L., is another common form on the Port Douglas 

 rocks. It is distinguished by a less oblique form than N. costata 

 the ribs are not so coarse, the columella concave, teeth on both 

 lips, fine and numeroas, and the whole shell is conspicuously 

 marked black and white in a varied style of ornamentation, of 

 which a broad, white, spiral band is the most common. It was 

 described from Eumphius by Linnaeus, who refers to the former's 

 figure. According to Hanley, type specimens are preserved in 

 the cabinet of Linnaeus. The habitat given is the Cape of Good 

 Hope and Indian Ocean, but the first locality may be erroneous. 



All the species have the peculiarity of keeping on the rocks 

 above tidal marks, like the Littorinm. The various species seem 

 to group together and keep very distinct ; the only wanderers 

 beingiV. alUcilla, which are sometimes found at the bottom of pools. 



There is one point of distinction between all the JSferitas, and 

 that is in the operculum. Shells that resemble each other in many 

 ways are found to have quite different opercula. I shall speak 

 presently of a characteristic instance of this when dealing with 

 the mangrove fauna. The opercula of N. poUta, N. costata, and 

 JV. alhicilla, are very characteristic. The latter though a more 

 finely marked shell than N. costata, has an operculum covered 

 with much coarser granulations. N. polita has a smooth and 

 beautifully polished operculum, with a defined margin of rugse. 

 This renders the sheU easy of identification. It has been long 

 known to naturalists. This we gather from the host of figures 

 quoted by Linnaeus. There is an exceptional uniformity in these 

 figures ; the type specimens still exist in the Linnean cabinets. 

 JSf. mollucensis is also found at Port Douglas, and some others to 

 be mentioned presently. 



Two species of Chiton are sufiiciently common on the rocks. 

 One appears te be the Chiton spinosus of Eeeve. The other may 



