THE FAMILY OF UNIONIDJB. XV 



to their identity, and therefore I hesitate. Some of these I have had for more tli.-ui 

 twenty years. 1 It should he rememhered that many of the diagnoses of my in-\v 

 species were made from single specimens, and these sometimes imperfect. The various 

 aspects and the differences of the characters of the old and young as well as that of 

 males and females, are often very imperfect, and necessarily therefore some arc omit- 

 ted. The important character of the undulations of the beaks is often omitted on 

 account of the imperfection of the part. 



Too much stress cannot he laid on the importance of keeping down the species 

 in all branches of Zoology. Prof. Owen has well remarked that "the coining of 

 names for things glanced at and imperfectly understood, the falsification of signs 

 without due comprehension of the thing signified, becomes a hindrance instead of a 

 furtherance of true knowledge." And Prof. Carpenter, in one of his lectures in 

 1859, said "there are too many who are far too ready to establish new species upmi 

 variations of the most trivial character, without taking the pains of establishing the 

 value of these differences, by ascertaining their constancy through an extensive 

 series of individuals; thus, as was well said by the late Prince of Canino, 'describ- 

 ing specimens instead of species,' and burdening science not only with a useless 

 nomenclature, but with a mass of false assertions. It should be borne in mind that 

 every one who thus makes a bad species is really doing a detriment to science, while 

 every one who proves the identity of a species, previously accounted distinct, is 

 contributing towards its simplification, and is therefore one of its truest benefactors." 

 Dr. Arnott, in Proceedings of the Royal Society of Edinburgh, very forcibly says that 

 "to indicate many apparently new species, is the work of an hour; to establish one 

 on a sure foundation, is sometimes the labor of months or years." 



To form a systematic, and, so far as possible, a natural arrangement of thi< 

 family, has long occupied my serious attention. 



I was, from my first knowledge of the Family, struck with the very different 

 aspect of the winged species, and, taking the hint of Lamarck, 2 I thought that an 

 important division could be made by separating the connate from the free shells, and 

 proposed the name of Sympliynota for such as were connate. I was not satisfied at 

 that time in separating a genus of this family by a character differing from that of 

 the teeth, but presumed that the family would be taken up by some one, if not by 

 myself, and that the first division of it would be symphynote and non-symphynote 



1 The observation of a late French writer that not more than three in one hundred of my species 

 will stand, is too flippant to need much notice. Time will prove that very few will be eliminated. 



2 Vol. vi. p. 76. 



