IV.]' INTRODUCTION. Ixix 



containing a preparation of gold or silver leaf for em- 

 blazoning. The valves of Pecten maximus and P. oper- 

 cularis make an ornamental as well as a usefal little 

 dish for scalloped oysters. Ormers are used in Guernsey 

 by farmers to frighten away small birds from the standing 

 corn^ two or three of these shells being strung together 

 and suspended by a string from the end of a long stick, 

 so as to make a clattering noise when moved by the 

 wind. Among other services which the Mollusca render 

 to man is their indicating an approach of rain or a 

 change of temperature. Several interesting facts with 

 respect to this hygrometrical property have been recorded 

 by Mr. B. Thomas of Cincinnati, U.S., in Dingler^s 

 ^ Polvtechnisches Journal : " and as I am not aware that 

 similar observations have been made or published in 

 Great Britain, I venture to direct the attention of 

 naturalists who live in the countrv to this curious 

 inquiry. Mr. Thomas states that snails are more 

 reliable than leaves as natural barometers ; that, in con- 

 sequence of their never drinking, all the moistm^e they 

 receive is by absorption of rain, mist, or dew through the 

 tissues of their bodies, and this thev afterwards exude 

 at regular intervals, until they obtain a fresh supply 

 that the colour of certain kinds of snail varies according 

 to the quantity of moisture retained ; that tAvo days 

 before rain is about to fall they climb trees, which they 

 never do on other occasions : and that when thev are 

 observed to leave the herbage and get on rocks, it is a 

 certain prognostication of wet weather. Not many 

 years ago some wonderful stories were afloat as to the 

 galvanic nature of snails, which it was proposed to 

 turn to account as a medium of communication between 

 distant friends ; but this mystery has been eclipsed by 

 that of spirit-rapping, with Which the molluscan phe- 



