174 Observations on Trilobites. 



Observations on the structure of Trilobites, and descrip- 

 tion of an apparently new genus. By J. E. Dtkay. With 

 Notes on the Geology of Trenton Falls. By Professor 

 James Renwick. Read Nov. 22nd. 



One of our associates on his return from the celebrated 

 Falls of Trenton, in this State, brought with him a Trilobite, 

 whose peculiar form and great size excited much cunosity. 

 By referring to the descriptions of authors, it was satisfactori- 

 ly ascertained to be different from any thing in the books. 

 As the specimen, was however, much weathered, imperfect in 

 some important parts, and had been accidently distorted, it 

 was deemed advisable to suspend further investigation until 

 more perfect specimens could be procured. 



At this juncture, Mr. John Sherman of Olden Barneveld, 

 arrived in this city, and exhibited to the Lyceum a collection 

 of Trilobites and other organic remains from Trenton Falls, 

 such as perhaps were seldom before assembled together. He 

 very generously enriched the cabinet of the Lyceum with a 

 beautiful series of these relics, and kindly permitted drawings 

 and casts to be made of those that he could not conveniently 

 spare. 



From these specimens we have been enabled to draw up 

 the following characters of a new genus of Trilobites, under 

 the name of 



IsOTELUS.* 



Body, oval-oblong ; often contracted, not unfrequently ex- 

 tended. 

 Head or buckler, large and rounded, equalling the tail in 



size, with but two oculiform tubercles. 

 Abdomen, with eight articulations. 

 Frontal process beneath with two semi-lunar terminations. 



* From i'tfog equal aDd TsXo^end, extremity. 



