20 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 'J2. 



During- the summer of 1919, Mr. Frank Springer resumed his 

 field researches upon the fossil echinoderms of the Ohio Valley, 

 which had heen interrupted by the war, with the special object of 

 securing- additional material from the remarkable crinoidal fauna 

 of the Laurel formation of the Niagaran for use in his monograph 

 on the Silurian crinoids. The principal work was done at St. Paul, 



Y\c. 19. — The type specimen ut Jsotrhis hracliyci-l^halus Foerste, 

 the largest known entire American trilobite. About ]4 natural 

 size. Photograph by Bassler. 



in Shelby County, Indiana, where Mr. Springer's assistant. Dr. 

 Herrick E. Wilson, continued the systematic collecting and 

 detailed study of the strata begun several years ago. Collecting 

 in the beds at this locality is laborious and difficult, and specimens 

 are not abundant, but they exhibit in some respects a strong paral- 

 lelism with those of the Swedish and luiglish Silurian, which renders 



