CONCHOLOGY. 



85 



P. granulans. 

 P. decaurata. 

 P. Magellanica. 

 P. stellifera. 

 P. vulgata. 

 P. Mammillaris. 

 P. lineata. 

 P. leucopleura. 

 P. notata. 

 P. Tarentina. 

 P. punctata. 

 P. puncturata. 

 P. Javanica. 

 P. tuberculifera. 

 P. miniata. 

 P. pellucida. 

 P. tricostata. 



P. Galathia. 

 P. pectinata. 

 P. viridula. 

 P. scutellaris. 

 P. radians. 

 P. cserulea. 

 P. plumbia. 

 P. umbrella. 

 P. pyramidata. 

 P. luteola. 

 P. aspera. 

 P. spinifera. 

 P. longicosta. 

 P. barbata. 

 P. angulosa. 

 P. saccharina. 

 P. laciniosa. 



P. plicata. 



5. Genus Umbrella. PI. IX. 



Animal. Body very thick and oval, provided with a dorsal 

 shell ; foot large, smooth and flat, surrounded b}' a border, ante- 

 riorly notched, attenuated behind ; head indistinct ; four tenta- 

 cula, the two upper ones thick, short, and truncated, the other 

 two thin, and shaped like pedunculated crests ; having foliaceous 

 branchiae. 



Shell. External, orbicular, subirregular, nearly flat, slightly 

 convex above, white, with apex near the middle ; margin acute, 

 internal surface rather concave ; having a callous disk, coloured, 

 depressed in the centre, surrounded by a smooth border. Inhabits 

 the Indian Ocean. Two species. 



Umbrella Indica. Umbrella Mediterranea. 



6. Genus Pleiirobranchus. PI. IX. 

 Animal. Body creeping, fleshy ; mantle and foot expanded ; 

 branchiae placed on the right side ; cloak enveloping the shell ; 

 neck short, contracted in some species, with an eraarginate front, 



