A N O M I A . 83 



scription which shall not be contradicted by some 

 among them. The perforation in one or other of 

 the valves, for the emission of a ligature^ by which 

 the animal adheres to extraneous substances, is 

 perhaps the most general, though not an universal 

 character. 



The name dvo[ji,iu, trans gressmi of the law, of- 

 fers the best apology for the incongruities of the 

 genus. It appears to be the general receptacle of 

 all shells which cannot scientifically be referred to 

 any other family. Of the species which now con- 

 stitute the genus, 3 divisions have been formed, 

 which may in some degree assist their methodical 

 arrangement, and explain to the learner the prin- 

 cipal points in which they differ. 



The best example of the 3d section is A. Sella, 

 which has been omitted in the plate through in- 

 advertence. 



