EXPLANATION OE TERMS. 295 



apply generally to shells, whether bivalve or univalve. A 

 few of these latter must terminate the present chapter. 



Aculeatedj having spines. Acuminated, terminating in 

 a point. Adnate is a word applied to the edges of some of 

 the JJniones, which are united and grow together ; this is 

 not the case with any British species. Many species of 

 Nayades, when young, have their dorsal margins adnate, 

 and, when fully grown, have them separate. A shell, or 

 part of one, is canaliculated when it has grooves or canals 

 in one direction ; it is cancellated when it has ridges cross- 

 ing each other in both directions ; it is carinated when it 

 has sharp keel-like edges ; and coronated when it is sur- 

 rounded, on an upper edge or angle, by a series of lobes or 

 spines. Any portion of the edge of a shell which is not con- 

 tinuous, but interrupted by a notch or sinuosity, is said to 

 be emarginated. The words fasciated, or banded ; fasci- 

 culated, or having little bunches of hair (as the margin of 

 Chiton fasciculatus) ; fimbriated, or fringed ; flexuous, or 

 winding ; foliated, or leaf-like, will scarcely present any 

 difficulty of application, wherever they may occur. 



The same may be said of the words ligulate, or tongue- 

 shaped ; maculated, or spotted ; ellijotical, or oval ; pal- 

 mated, or flattened, as the fronds of some Spondi/li and 



