8o Aug. F. Foerste 



that the number as a whole appeared before the close of September 

 of that year. The article on North American trilobites begins on 

 page 558. A break occurs at the close of this article ,on page 560. 

 and it would have been possible to distribute the earlier pages of 

 this number, evidently printed before the trouble widi the publishei 

 became serious (page 566), without awaiting the completion of the 

 number, but there is no evidence that this was done. 



Crvptolithus tcsscUatus, Green, publishe.d on page 560, evi- 

 dently is the same species as Triuncleus concentricus, and of this 

 there never has been any doubt. The generic characteristics, con- 

 sidering the date of publication, are clearly indicated. The genus 

 and species were founded upon a specimen collected by Hall from 

 the slates of the Lorraine beds at Waterford, New York, and still 

 in the possession of Hall at the time of publication of volume i. 

 New York Paleontology. 



The same specimen was used by Prof. Amos Eaton in describ- 

 ing Nuttainia concentrica, although in this description the Trenton 

 locality at Glennsfalls is mentioned first. The description appears 

 on page 33 of the second edition of Eaton's Geological Text hook, 

 dated June 15, 1832. Unfortunately, the date of a preface is no 

 indication of time of publication of a book, beyond the fact that 

 the latter usually is later. There is no doubt that Green's Mono- 

 grapli of North American Trilobites, dated October i, 1832, ap- 

 peared later than Eaton's Geological Text book, but on page 88 

 of his Monograph Green states the genus Cryptolithus was pro- 

 posed before the appearance of Eaton's work, evidently in his 

 Synopsis, published in the Monthly American Journal. That this 

 is possible is shown by the fact that some geological libraries con- 

 tain copies of the Monthly American Journal of Geology and 

 Natural Science which terminate with the close of Green's Mono- 

 graph, and do not contain the following pages. One of these 

 copies is in the Library of the Walker Museum, at Chicago L^ni- 

 versity, one of the very rare complete copies also being present. 



There is no question that the genus Nuttainia was founded 

 upon the species usually called Trinucleus concentricus, and there 

 is no confusion in the generic description, as the following quota- 

 tion from Eaton's text-book will show : 



Nuttainia. Head in three lobes, the middle one most prominent; the two 

 lateral lobes, sub-hemispherical or sub-quadrantal : the whole head bordered 

 anteriorly with a punctured fillet; bod}' distinctly three lobed, middle lobe sub- 

 cylindric, and not so broad as the side lobes. 



