VI PREFACE. 



Doctor Troost's work as a paleontologist reveals the accurate 

 observation and logical interpretation of the trained naturalist, and 

 while erroneous in some minor particulars, is yet remarkably good 

 when one considers the almost unknown path he followed in this 

 field of science. The monograph on the crinoids of Tennessee was 

 the last of his scientific labors, and was performed with some diffi- 

 culty, as shown by the pathetic reference to his failing health at the 

 end of Ins introductory description of the geology of Tennessee. His 

 death occurred on August 14, 1850, only four weeks after his mono- 

 graph was completed and sent to the Smithsonian Institution for 

 publication. 



Doctor Troost brought to the new world a wide experience and 

 broad culture obtained in the riper civilization of the old, and to this 

 he added high character and a public spirit winch made him a valu- 

 able acquisition to the life of his adopted country. 



The following revision of Doctor Troost's monograph on the 

 crinoids of Tennessee was prepared at the request of the authorities 

 of the United States National Museum. The reasons for the long 

 delay are given in the introductory paragraphs of the bulletin. 



This work was begun while the writer was connected with the 

 United States Geological Survey as assistant in paleontology, and 

 has been completed at Columbia University, where it was presented 

 as a thesis in connection with the degree of master of arts in 1908. 



Elvira Wood. 



