Handbook of Paleontology 321 



Rhytimya, Cyrtodonta etc.), gastropods (Pleurotomaria 

 sp., Hormotoma sp., Lophospira litorea, Bucanella trilo- 

 bata) and cephalopods (Oncoceras gibbosum, Orthoceras 

 sp.). The characteristic ostracod (crustacean) Leper- 

 ditia cylindrica also occurs. This fauna in its pelecy- 

 pods exhibits decidedly Richmondian (Lower Medina) 

 affinities, and they constitute considerably more than a 

 majority of the total number of species. 



The Clinton beds or formation (Vanuxem '42) was 

 named from the type section at Clinton, Oneida county, 

 and has a maximum thickness of 350 feet. In this group, 

 as a basal deposit, is now included the Thorold sandstone 

 and Oneida conglomerate previously regarded as the top 

 of the Medina. The members of the Clinton formation 

 extend as a belt from Otsego county to the western 

 limits of the State and form the" lower part of the 

 Niagaran series (Clarke and Schuchert '99, from the 

 Lockport (Niagaran) limestone), the upper part being the 

 Lockport group with the Guelph dolomite as the top 

 member of the formation (figures 45, 46). 



The Clinton group in New York is divisible into three 

 main parts, termed for the present Lower Clinton, Middle 

 Clinton and Upper Clinton ; and each of these formations, 

 except perhaps the middle one, is again divisible into two 

 or more lithological members (Hartnagel '12; Chadwick 

 '18). These three divisions of the Clinton differ very de- 

 cidedly in geographic distribution and are distinguished 

 by strongly marked faunal differences which are main- 

 tained and clearly recognizable from New York to Ala- 

 bama. Ulrich's studies of the ostracods have for the first 

 time cleared up the confusion that before existed in the 

 correlation of the Clinton beds (Ulrich and Bassler '23; 

 342-49). Study of the field relations of the Clinton ostra- 



