43 



of both number of species and individuals in the Silurian 

 period. The quarries of the Waterlime, near Buffalo, 

 N. Y., have yielded many specimens. The fragment 

 exhibited represents an individual of unusually large 

 size. 



8. Black River and Trenton Limestone Fossils from the 



Lake Champlain Valley. 



Exhibited by Theodore G. White, Columbia University. 



The invertebrate fossils show^n are selected from a 

 large collection which is the basis of a forthcoming 

 monograph on the stratigraphy of the Champlain Tren- 

 ton formations. 



I. Brachiopods. 



a. Series of the species and varieties of the genera 

 Strophomena and Rafinesquina. 



b. Series showing variation in forms of Orthids and 

 Plectambon ites. 



c. Various species of Lingula^ Trematis and other 

 inarticulate forms. 



2. Trilobites. Sets illustrating forms of the 

 genera : 



a. Asaphus. d. Trinucleus. 



b. UlcBnus. e. Ceraurus. 



c. Triarthi'us. f. Pterygojnetopus . 



9. Models of Trilobites. 



Exhibited by Prof. Charles E. Beecher, Yale University 

 Museum, New Haven, Conn. 



I . Recently definite knowledge has been obtained re- 

 garding the anatomy and affinities of Trilobites. Their 

 relationships are with the Crustacea of which they form 

 the most primitive division. They may, in a general 

 way, be considered the ancestors of the modern lobsters, 

 shrimps and crabs. 



The models exhibited show the results of the latest in- 

 vestigations regarding the structure and appendages of 



