LUCINID.E. 231 



different genera- have been described from various parts 

 of the world ; and fossil species are still more abundant. 



The " family likeness " is unmistakeable, and this 

 constitutes part of the value of the Lucinidce as a 

 natural group. After much consideration and study of 

 the question, and with great respect for the opinion of 

 the authors of the f British Mollusca' and of M. Des-. 

 hayes, I cannot agree with them that the long-esta- 

 blished genera of Loripes and Aocinus ought to be 

 merged in Lucina. The great French conchologist has 

 lately made a strong protest against the dismemberment 

 of the last-mentioned genus; and he wishes it to be 

 retained, like the once glorious republic of his own 

 country, " une et indivisible." To use his own words, 

 it forms " une grande unite." It may, however, be 

 questionable if the characters on which he lays so 

 much stress do not apply not only to the genus, but to 

 the family which has sprung from it, and whether there 

 are not other characters, although perhaps of inferior 

 value, that may serve to distinguish several genera. I 

 believe that such characters exist, and I will endeavour 

 to point them out in the proper place. It can hardly 

 be disputed that each group of natural objects, whether 

 we call it a kingdom, class, order, family, genus, species, 

 or variety, has some peculiar feature of its own, although 

 we may not be able to detect it. The imperfection of 

 our knowledge has hitherto combined with the limited 

 capacity of our intellect in keeping us but partly en- 

 lightened ; and this must ever continue to be the case, 

 until the whole scheme of Nature, past and present, has 

 been unfolded to our view. Perhaps, even to the greatest 

 philosopher of modern days, 



" Science appears but what in truth she is, 

 Not as our glory and our absolute boast, 

 But as a suecedaneum, and a prop 

 To our infirmity." 



