82 FIFTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



PREIiIIfII]\ARY IVOTICE 



OF THE 



TRILOBITES AND OTHER CRUSTACEA OF THE UPPER ' 

 HELDERBERG, HAMILTON AND CHEMUNG GROUPS. 



[Published September 1861.] 



The Trilobites were among the fossils which early attracted the 

 attention of American and other naturalists; and specimens had 

 been sent by Prof. Bucatel of Maryland and Dr. Hosack of New- 

 York to Prof. Brongniart at Paris, and were in his hands when he 

 published his " Histoire JVaturelle des Crustaces fossiles.^^ Among 

 those who have described trilobites from the rocks of the United 

 States, and particularly from New-York, or species known in this 

 State, are Mr. Stokes, Dr. Bigsby, Dr. De Kay, Dr. Jacob Green*, 

 and Prof A. Eaton. During the Geological Survey of this State, 

 Mr. Conrad described several species in his annual reports upon 

 the palaeontology; and others have been published in the first, 

 second and third volumes of the Palaeontology of New-York, em- 

 bracing those known in the Lower and Upper Silurian strata. The 

 following species are all that are at present known to me in the 

 higher groups, or the rocks corresponding to the Devonian System 

 of Europe. 



TRILOBITES. 



GENUS CALYMENE (Brongniart). 



CALYMENE PLATYS (Green). 



Calymene platys : Green, Monograph, p. 32. 



This species was described by Dr. Green from a cast taken in a natural 

 mould left by the fossil in the rock, which is its more common mode of 

 occurrence. Since that time, two or three specimens of the fossil, retaining 

 portions of the crust, have been found at Schoharie by Mr. Gebhard, and 

 are now in the State Cabinet. 



The form is similar to C. hlumenbachii; but certain differences, and 

 particularly the form of the hypostoma, distinguish it from that species. 



Geological formation and locality. In the Schoharie grit : in the Hel- 

 derberg mountains, and at Schoharie. 



• Monograph of the Trilobites of Korth America, with colored models of the species 

 Sj Jacob Gseen, M.D. etc. 1822. 



[SeptfiZfiiicir 



