44 Field Museum of Natural History — Geology, Vol. IV. 



were determined. A number of species of crinoids and cystoids, prob- 

 ably six or eight species of which Savage made no mention, were also 

 found. Of the twenty species of trilobites twelve were found to be new 

 and are here described and figured. Five of the eight species which 

 have been previously described are here redescribed and figured. The 

 remaining three species were too fragmentary to admit of description. 



Thus far the only group that has been critically studied by the 

 writer is the trilobites and the finding of so many new species in that 

 group would indicate that when the other groups are studied new 

 material will be discovered. A beginning has been made on the echino- 

 derms, and so far none of them appears to be referable to known species. 

 If they prove to be new, they will probably be described in a future 

 paper. 



CLASSIFICATION AND TERMINOLOGY 



The classification here used is that prepared by Prof. Charles E. 

 Beecher and given in the English edition of Zittel's Text Book of Paleon- 

 tology. For definitions of the 

 various orders and families the 

 reader is referred to that work. 



In order to make clear in 

 what sense various terms are 

 used by the writer, the follow- 

 ing glossary is given. The 

 letters or figures in parentheses 

 refer to text figure i. 



Annulations: The ring-like 

 divisions of the axis of the 

 pygidium. (13) 



Anterior: Situated in front. 



Anterior limb of the facial 

 suture: The portion of the facial 

 suture lying in front of the 

 eye. (2) 



Axis: The median longitu- 

 dinal lobe of a trilobite. (a). 



Carapace: The hard shell 

 covering the dorsal surface of 

 a trilobite. 



Caudal spine: A spine at 

 the posterior extremity of the 



Figure 1. Diagrammatic figure of a Trilobite. pygldlUm. (12) 



