﻿H. S. Williams — Lamellibranckiata and Species-making. 195 



of generic types or representative species of those genera, and 

 34 genera were illustrated ; when we compare it with the final 

 report, published only one year later, we find 19 cases of 

 changed generic identifications, or, proportionate to the number 

 of genera 50$, and 24 specific changes or nearly 35$. 



Both these works, the plates and explanations, 1883, and the 

 generic illustrations, 1884, were issued by the State Geologist 

 as authoritative works illustrating the typical specimens, de- 

 scribed mostly by him, in the State collections; specimens which 

 had been picked out as typical for the draughtsman, and not 

 only had they been identified by him, but they had been used 

 in the very descriptions of genera and species for the illustra- 

 tion of which they were published. 



In the final work, 1885, their generic and specific names are 

 changed, in most cases with no reason given, occasionally with 

 the note " by error" inserted in the list of synonyms. These 

 alterations are not a simple few, but for the plates and ex- 

 planations, there is an average of one alteration of identifica- 

 tion for every species in the book. There is no disputing the 

 facts ; anyone can find them by mere comparison of the two 

 volumes. 



It seems impossible to suppose that such errors could be due to 

 carelessness of observation ; the life-time experience of the 

 author, and his acknowledged first rank among paleontolo- 

 gists forbid such an explanation, and we have no reason to 

 suppose that the identifications are not in all cases his own. 



The only explanation we can conceive of is found in the 

 system itself upon which the species are conceived and defined. 

 Species-making and illustrating fossil forms are not the same 

 thing. To have good figures of the most perfect typical fossil 

 forms is of the greatest value to the student of paleontology but, 

 if they are classified into species and genera it is all important 

 that the differentiating characters should be discernible, at least 

 on the typical specimens, and that too, not by experts only, but 

 by any ordinary intelligent observer. 



When we see 57 species made of a group of fossils, in which 

 the surface is practically without differentiating characters, all 

 the elements of form the same, showing only differences in con- 

 tour, with a slight range of difference in convexity and in the 

 angle made by the umbonal ridge with the cardinal margin, and 

 in the points used for specific distinction with scarcely two 

 specimens alike, we think it is asking too much of students to 

 accept the species as of value, or to expect him to recognize 

 them. Our hesitation is confirmed when, as in the case of 

 the genus " Leptodesma" we read, as the most important dis- 

 tinctive character of the genus, that " the anterior end is always 

 nasute and acute instead of auricular and rounded " (as in 



