Observations on Trilobites. lbD 



Professor Wahlenberg supposes that the branchial appara- 

 tus was most probably placed under the middle lobes of the 

 abdomen, and the feet to have been situated beneath the head 

 or buckler. 



Trilobites, according to Professor Wahlenberg, were fur- 

 nished with short feet, which served at the same time, as ac- 

 cessary organs of mastication. He assigns as a reason why 

 they have never yet been discovered, that most of the remains 

 now found, are the exuvia of Trilobites, in which these parts 

 of course, would not easily be discovered. Those only he 

 considers as perfect animals, which are found rolled up on 

 themselves ; and in these alone can we expect to find the feet 

 of Trilobites. " 



In a supplement to this paper, he has described and figured 

 two species, Entomostracites crassicauda, and E. exienuatus, 

 which appear to belong to the Genus Isotelus. 



Geology of Trenton Falls. 



Situation. Upon West Canada Creek, near the village of 

 Olden Barneveld, and about 13 miles north of Utica. West 

 Canada Creek is one of the principal branches of the Mohawk 

 river, it rises on the confines of Hamilton and Herkimer 

 Counties, and falls into that river near the village of Herkimer. 



Depth and extent of formation. The river has worn itself a 

 passage through the rock for the distance of nearly two miles, 

 forming a series of water-falls, and has thus laid open to 

 view the strata to a depth of probably 300 feet. The layers 

 thus disclosed, are nearly horizontal, and of various thick- 

 nesses ; they are composed of limestone, with the exception 

 of numerous thin veins of argillaceous matter. The scenery 

 in the glen, worn by the stream, is of the most picturesque and 

 romantic character. From the high land, seven miles north 

 of Utica, this rock appears to form an unbroken ridge of 

 nearly equal height for many miles, extending from the valley . 



