12 PREFACE. 



is not always giveu, only tlie more important localities being cited. In 

 every case, however, the locality first mentioned is believed to be the 

 original one. 



For the proper generic disposition of the species the work of Hall 

 and Clarke^ lias been closely followed, and the entire synopsis is 

 arranged alphabetically to facilitate easy finding. The geologic dis- 

 tribution of the genera is given at the end of Chapter I, and their sys- 

 tematic position in the classification in Chapter V. The evolution of 

 the lophophore, from the simple cresceutic condition with few tentacles 

 of theprotegulum to the most complex condition in the Terebratulacea, 

 described in Chapter IV, is wholly the work of Dr. Beecher. From the 

 development of this organ in recent species the peculiarly complicated 

 growth of the lophophore in the Spiriferacea is also explained. Some 

 of the embryonic brachial conditions are likewise i^idicated as proba- 

 bly existing in a mature condition in early Paleozoic genera. 



The danger of neglecting young or small specimens of any organism 

 can not be too often impressed upon collectors. Often by means of such 

 fossils intricate problems in phylogeny or life history may be solved. 

 To have much value, however, young specimens must be very small, 

 and these can not be picked up in the field. Where brachiopods 

 abound, whether in clay or of a siliceous nature in limestone, material 

 should be collected in bulk and prepared later by washing or etching 

 with weak muriatic acid. This method of collecting generally results 

 in securing fossils that otherwise will not be observed. 



To Dr. Charles E. Beecher, of Yale University Museum, the best 

 thanks of the writer are especially due for the continued interest taken 

 in this catalogue, as well as for valuable suggestions regarding classi- 

 fication ; and to Mr. Charles D. Walcott, Director of the United States 

 Geological Survey, for favors relating to the publication of the paper. 



To the following gentlemen the grateful acknowledgments of the 

 writer are due for specimens or for suggestions in synonymy: Prof. 

 J. F. Whiteaves, Canadian Geological Survey; Prof. H. S. Williams, 

 Yale University, Director Charles D. Walcott, Dr.W.H.Dall,Dr.T. W. 

 Stanton, and Dr. George H. Girty, United States Geological Survey; 

 Prof. E. P. Whitfield, American Museum of Natural History; Prof. 

 N. H. Winchell, State geologist of Minnesota; Mr. E. O. Ulrich, Kew- 

 I)ort, Kentucky; Mr. S. A. Miller, Cincinnati, Ohio; Mr. R. R. Rowley, 

 Louisiana, Missouri, and Mr. D. K. Gregor, Fulton, Missouri; and to 

 Dr. C. Davies Sherborn, of the British Museum, for valuable sugges- 

 tions in bibliography. 



C. S. 



'Palaeontology of New York, Vol. VIII, 1892-95. 



