canal near Cahooes Falls, in the State of New York, 

 and at a number of other places in that State. 



I have named this species in compliment to my 

 early friend, Professor Theodore Romeyn Beck, M. D. 

 well known both at home and abroad, as the learn- 

 ed author of the work on Medical Jurisprudence. 

 Some time after commencing this little Monograph, 

 I communicated my plan to Dr. Beck, and was sur- 

 prised and gratified to find that he was also engaged 

 with the same inquiries, and that he was then busy 

 in arranging and examining the unique collection of 

 trilobites belonging to the Albany Institute. With- 

 out the smallest hesitation, he placed all his speci- 

 mens at my disposal, and has facilitated otherwise 

 my undertaking, by every means in his power. 

 



GENUS NUTTAINIA. Eaton. 



Professor A. Eaton, in his Geological Text Book, 

 has proposed the Genus Nuttainia, to include two 

 remarkable trilobites which could not properly be 

 arranged in any of the previously established genera. 

 The two fossils here grouped together, bear no gene- 

 ric relation to each other. The first species which 

 he calls N. Concentrica, belongs to the genus Crypto- 

 lythus, which was proposed before the appearance of 

 his work, and has therefore been noticed in another 

 place. 



The genus Nuttainia is thus characterized by its 

 author: " Head in three lobes, the middle one most 

 prominent ; the two lateral lobes sub-hemispherical, 



