The Tritons and Prog Shells 



distributed widely in warm seas. D. cancellinus, Roissy, is the 

 type. 



D. anus, Linn., has a very small aperture, from which the 

 enameled lips flare into a white ruffled border, almost as wide as 

 the body of the shell. There is scarcely any canal. The surface 

 is cancellated, with brown bands on a white ground. Length, 

 2 to 3 inches. 



Habitat. — Red Sea Indian Ocean, Philippines. 



THE FROG SHELLS 

 Genus RANELLA, Lam. 



The Frog Shells are mostly large and heavy, with surface 

 granulated and tuberculated. Possibly this warty appearance 

 accounts for the name. Possibly it is the squat shape of some 

 species, with their sprawling leg-like tubercled processes. The 

 genus is distinguished from the Tritons by the uniform presence 

 of a varix on each half coil of the shell. These form thick ridges 

 on opposite sides, making the shells distinctly two-edged. 



The genus of about fifty species is distributed in tropical seas. 

 The animals are active in movements, creeping on the broad foot 

 over coral reefs and rocks. 



The Spiny Frog Shell (R. spinosa, Lam.) has two thorn- 

 like tubercles on each of its varices, and short, sharp spines on 

 the ridges between. The shell is stout, with short spire and canal, 

 and ovate aperture. Colour, light brown mottled with darker. 

 Length, 2 to 3 inches. 



Habitat. — Mauritius, Indian Ocean, Philippines. 



The Californian Frog Shell (R. Calijornica, Hds.) is a fine 

 species, 2^ to 4 inches long, with heavy, strongly ridged and tuber- 

 culated shell, turreted spire, wide aperture, with flaring lips, and 

 short anterior and posterior channels. The colourless surface is 

 irregularly banded with chestnut; the lining is faintly rosy. 



Except for its greater thickness and stronger development 

 of nodules, this species might be mistaken for R. ventricosa, Brod., 

 a Peruvian species with an exceedingly thin shell. 



Habitat. — Southern and Lower California. 



The Lamp Ranella {R. lampas, Linn.), the heaviest shell 



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