MARCELLUS LIMESTONES OF LANCASTER 175 



fauna, was succeeded by a limestone-making epoch with clearing 

 waters, and a typical Hamilton fauna which had migrated from 

 some, at present, unknown locality. This was followed by a 

 return of the Marcellus fauna when the waters were again more 

 shallow and less pure. 



The existence of a Hamilton fauna in the Stafford limestone 

 at Stafford and Livonia has already been noted by John M. 

 Clarke.^ His list of species for both localities comprises two 

 Anthozoa, one Crinoid, four Bryozoa, 27 Brachiopoda, 10 Lamelli- 

 branchiata, 14 Gastropoda, one Pteropod, 10 Cephalopoda, six 

 Arthropoda and one Annelid, a total of 76 species, of which two 

 Bryozoa, 16 Brachiopoda, three Lamellibranchiata, five Gastro- 

 poda, two Pteropoda, three Cephalopoda, and three Arthropoda, 

 a total of 34 epecies, have been found at Lancaster, that is, 

 about half the total fauna of the Lancaster limestone is present 

 in the Stafford limestone. The most characteristic species of the 

 section under consideration are S t r o p h a 1 o s i a t r u n c a t a, 

 S p i r i f e r s u b u m b o n a , IM e r i s t e 1 1 a b a r r i s i , C a m - 

 arotoechia eappho, Phacops rana, Orthoceras 

 marcellense, O. exile, Liorhynchus limitare, 

 Reticular ia fimbriata, and Cypricardinia in- 

 dent a, of which the first six are found in the Stafford lime- 

 stone. 



A comparison of material from the Stafford limestone of these 

 localities in the New York state museum at Albany reveals a 

 close correspondence in lithologic character and fossils with 

 beds VII and YIII, 15 species restricted to these two upper beds 

 being found in the Stafford limestone. Liorhynchus 

 limitare which is common in the lower beds is absent from 

 the three upper beds of the section and absent also from 

 the sections cited. The thickness of this limestone is given as 

 from 18 inches to 2 feet, while the combined thickness of beds 

 VII and VIII is 2 feet 2 inches. These facts seem to warrant 

 a definite correlation of beds VII and VIII with the 2 feet of 

 limestone exposed at Stafford. 



1 In wi<rk cited, and Succession of the fossil faunas in the section of the Livonia salt shaft; 

 N. Y. state geol. 13th an. rep't. 1894. p. 131. 



