Handbook of Paleontology 331 



ton species. At Clinton in the limy zone above the ore 

 occur the brachiopods Dalmanella elegantula, Bilobites 

 biloba, and Nucleospira pisiformis, prolific members of 

 the two succeeding formations (Irondequoit, Rochester). 

 The coral Palaeocyclus rotuloides is abundant and strik- 

 ing, and the ostracods Mastigobolbina punctata and 

 Plethobolbina typicalis also occur here. The Irondequoit 

 limestone (Hartnagel '07) was named from the town of 

 Irondequoit, Monroe county. The formation is still 

 recognizable east of Wayne county, but has become so 

 shaly as to be no longer recognized as a limestone. In 

 the Niagara section the limestone directly overlies the 

 Reynales limestone (Wolcott of authors). This mem- 

 ber is a light gray, coarsely crystalline limestone with a 

 maximum thickness of 15 to 17 feet and consists of nu- 

 merous layers of limestone separated by bands of shale. 

 It is also characterized by the occurrence of reef struc- 

 ture, some confined to the limestones and others running 

 up into the Rochester shale above. Its highly fossili- 

 ferous character is in contrast to the limestone forma- 

 tions below. More than 100 species have been recorded 

 from the reefs, the most abundant being the brachiopod 

 IV hit field ell a nitida and the trilobite Illaenus ioxus. 

 Other common forms include the brachiopods Atrypa 

 reticularis, Camarotoechia neglecta, Spirifer crispus, 

 Leptaena rhomboidalis and the trilobite Calymene niag- 

 arensis. 



The Rochester shale member of the Clinton formation 

 consists of soft bluish gray argillaceous shale (Hall '39; 

 Conrad) with a maximum thickness of about 100 feet. 

 The shales were named from the city of Rochester. For 

 a time they were known as the Niagara shales, and then 

 the name of Rochester shales was revived. In the 



