N0.12C5. SYNOPSIS OF THE NAIADES SIMPSON. 513 



impossible to tell which of two names appeared first, and in such cases 

 I have nsed that which seemed to be best known. 



Many of the species of Lamarck stand on about the same foundation 

 as those of Rafinesque, having only a brietf description and no fig- 

 ures. Dr. Lea on at least two occasions went over the types of most 

 of Lamarck's species and has published his conclusions in the Obser- 

 vations, and I am obliged to abide by his decisions, never having seen 

 the types myself. 



One of the most perplexing problems has been the work done by 

 European conchologists, and especially by the so-called new school of 

 France. Previous to 1870, the date of issuance of Lea's last edition of 

 the synopsis, thousands of names had been applied to the few species 

 of Europe. But this work was conservative and reasonable compared 

 with that of the new school since then. I have devoted much time 

 and study to this fauna and its literature. To me it seems that 

 there are not more than eighteen or twenty species of Unionid;e found 

 in Europe, judging by the same standards I have applied to species 

 elsewhere. Nearly all the authors seem to be more or less at sea as to 

 certain forms of this area, and the reasons for this are probably their 

 want of striking characters and their extreme variability. Unio picto- 

 rwm, tumidus, elongatulus, and platyrhynchoideus have been often taken 

 for each other. Margaritana margaritifera has repeatedly been mis- 

 taken for the very similar looking M. crassa, and each of these has been 

 hopelessly confused with Unio batavus. * 



I have endeavored to consider names applied before 1870 in my 

 synonymy. I have made no effort to do this with those applied by 

 authors to the forms of Europe since that time, as I do not believe that 

 any new species of Unio, Margaritana, Anodonta, or Leguminaia have 

 been found there in the last thirty years. The genus Colleioptenim (1881) 

 is a doubtful one and is very likely only an mutation of the excessively 

 variable Anodonta cygnca. In 1892 Arnould Locard, one of the great 

 lights of the new school, stated that there were 208 species of Unios 

 and 250 Anodoutas in France alone. 1 



Life is too short and valuable to be wasted in any attempt at 

 deciphering such nonsense, and I have not even cumbered the pages 

 of this work with a list of these new species. Those interested can find 

 them in the works of Westerlund and Kobelt. 



In cases where the new school has worked on the fauna of Africa or 

 Asia, I have done the best I could to straighten out the synonymy. 



1 have not attempted to make any analytical key to genera and other 

 groups, because I do not believe that it is possible to construct a key 

 that will be of any real service to the student. At least four-fifths of 

 the shells of the Xaiades have the beaks so eroded that it is impossible 

 to form any idea of what their sculpture is like, and the soft parts are 

 inaccessible to the average student and collector. These are both vital 

 characters that must be used in classification. The general arrange- 

 ment of the groups down to genera is shown in the following table : 



1 Aim. Soc. Ag. Hist. Nat. Lyon, 1892, p. 55. 

 Proc. X. M. vol. xxii 33 



