PHILLINE. 21 '5 



flattish discs : one,, a lobe turned back over the head ; another^ 

 the mantle enveloping the shell ; and the two side lobes 

 of the foot, capable of great use in swimming. The plates 

 of the stomach, resembling those of Scaphander, seem to in- 

 dicate similar habits in the animal, although the shells are 

 so different, and one internal and the other external. The 

 shell of 

 P. quadrata is small, wdiite, spirally striated, with a series 



of minute holes. It is broad and rather square. 

 P. scahra : minute, white, punctured in spiral lines, with 

 the outer lip toothed : shaped like Scaphander lignaria. 

 P. catena : very minute, wdiite, with chain-like spiral sculp- 

 ture. 

 P. punctata : nearly oval, minute, punctured in squares. 

 T.pruinosa: slightly coloured with brown, frosted or sha- 

 greened ; rather globose. 

 These creatures, although so minute, have been carefully 

 examined by Mr. Clark in a living state. That gentleman, 

 in detailing his interesting observations in the ' Zoological 

 Journal,' remarks, with regard to P. pnunosa, that the foot 

 is very large when not turned over the back of the animal : 

 that the digitations at the end of the body are used in as- 

 sisting locomotion ; that the animal flaps the sides of its foot 



