NATURAL SCIENCES OF PHILADELPHIA. 177 



CATALOGUE OF THE RECENT SPECIES OF THE CLASS BRACHIOPODA. 

 BY W. H. DALL, U. S. COAST SURVEY. 



The following catalogue contains all the species known in a 

 recent state uj) to the date of writing. The synonymy does not 

 profess to be complete, but only sufficiently so to indicate the 

 history of each species approximately, with a reference whenever 

 possible to at least one good figure. 



It is probable that some of the species, especially of the genera 

 Lingula and Discinisca^ ma^y be reduced to the rank of s^^nonyms 

 by a careful comparison of types. I have thought it best to leave 

 this work, however, to some one who may have the opportunity of 

 comparing the specimens themselves. I feel confident, also, that 

 the number of species of Kraussina has been exaggerated. With 

 regard to the other groups, they appear to have been sufficiently 

 reduced, and the species here enumerated appear to be well de- 

 fined. Most of them I have been able to examine critically. 



While deprecating the multiplication of specific names on the 

 one hand, on the other the practice, miscalled conservatism, which 

 leads to the confounding of allied but distinct forms, from care- 

 lessness in comparison or the want of material for critical exami- 

 nation, cannot be too strongly condemned. Such a course leads 

 to the destruction of that critical exactness which is the basis of 

 all science, and onh^ furthers the convenience of the careless or 

 indolent investigator, at the sacrifice of accurac}^, and the great 

 increase of labor for the more careful and painstaking student. 



Those who may be led to examine this catalogue carefully will 

 trace the evil eflfect of both courses in the synonymy of many of 

 the species, and, while absolute accuracy seems unattainable, I 

 may be permitted to hope that herein at least a step has been 

 made in that direction. Great care has been taken with the locali- 

 ties attributed to the several species, and they are believed to be, 

 in the main, correct. 



I am under obligations to Mr. George W. Tryon, Jr., for assist- 

 ance in completing the synonymy. 



