A DICTIONARY OF TERMS. 



Jv 



Hinge. 



Hispid, 



Imbricated 



Imperforated. 



Impression. 



Inequilateral. 



Ineouivalve. 



Involute. 



H. 



The part under the summits, by which the sides 

 of bivalve and multivalve shells are connected 

 together. The hinge in most shells is toothed, 

 but in some it is without teeth, as in Oysters 

 and Muscles. 



Covered with hairs. The Helix hispida is an 

 example. 



I. 



Tiled. Shells are sometimes covered with scales, 

 which impend over each other like tiles on a 

 house. The ribs of the Cardium Isocardia 

 are covered with imbricated scales. The valves 

 of the Chiton are imbricated, or laying one 

 over the other. 



Which has no hole, that is, is not pierced. The 

 Limpets are, for the most part, imperforated. 



A trace, or mark. The muscles with which 

 the animals of bivalve shells are provided, 

 leave a mark in the interior, which is called 

 the muscular impression. Oysters have but 

 one muscular impression, the Veneres have two, 

 and some shells three muscular impressions. 



Of unequal sides. Inaequilateral valves are 

 those whose summits are farther from one end 

 of the shell than the other. The Tellens, are 

 generally inaequilateral. 



Of unequal valves. Having one valve more 

 convex, or of a different form from the other. 

 The PectenSy the Oysters, and the Spondyles, 

 are inaequivalve. 



Without spires. The Limpets are involute. 



J. 



Juxtaposition. A successive and perpetual adjunction of cal- 



