. The Cambridge natural history. Zoology; Zoologia Geral. r INTERMEDIATE FORMS Fig. 14.—Examples of the Auriculi- dae: A, Auricula Judae Lam., Bor- neo ; B, Scarabus Lessoni Blainv., E. Indies ; C, Cassidula mustelina Desh., N. Zealand ; D, Melampus castaneus Miihlf., S. Pacific ; E, Pedipes quadvidens Pfr., Jamaica. have 5^et never become, in respect of habitat, genuine fresh- water species. Like Potamides^ they haunt salt marshes, man- grove swamps, and the region about high-water mark. In some cases (0^/via, ^lelampus, Pedipes') they live on rocks which are moistened, or even bathed
. The Cambridge natural history. Zoology; Zoologia Geral. r INTERMEDIATE FORMS Fig. 14.—Examples of the Auriculi- dae: A, Auricula Judae Lam., Bor- neo ; B, Scarabus Lessoni Blainv., E. Indies ; C, Cassidula mustelina Desh., N. Zealand ; D, Melampus castaneus Miihlf., S. Pacific ; E, Pedipes quadvidens Pfr., Jamaica. have 5^et never become, in respect of habitat, genuine fresh- water species. Like Potamides^ they haunt salt marshes, man- grove swamps, and the region about high-water mark. In some cases (0^/via, ^lelampus, Pedipes') they live on rocks which are moistened, or even bathed by the spray, in others (Cassidula^ Aiiri- cula) they are immersed in some depth of brackish water at high tide, in others again (^Scarabus') they are more definitely terres- trial, and live under dead leaves in woods at some little distance from water. Indeed one genus of diminutive size (Carycliiuni) has completely abandoned the neigh- bourhood of the sea, and inhabits swampy ground almost all over the world. To this same section Gehydrophila have been assigned two remarkable forms of air-breathing "limpet," S'qjiionaria and G-adinia (see page 151), and the aberrant Amphih^la^ a unique instance of a true operculated pulmonate. Sipho- naria possesses a pulmonary cavity as well as a gill, while G-adinia and Amphihola are ex- clusively air-breathing. Sip^lionaria lives on rocks at or above high-water mark, Gadinia between tide marks, Amphihola (Fig. 15) in brackish water at the estuaries of rivers, half buried in the sand. There can be little doubt that all these are marine forms which are gradually becoming accustomed to a terrestrial existence. In Gadinia and Aynphihola the pro- cess is so» far complete that they have ex- changed gills -fer *a pulmonary* cavity, nvhile in* "Siphonaria we have an intermediate stage in which both organs exist together. A curious parallel to this is found in the case of Ampullaria^ which is furnished with two gills and a pulmona
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
