RAYMOND: CORRELATION OF THE ORDOVICIAN STRATA. 2-4:9 



graptiis tenuiramosus, are restricted to that locality and the Fulton of 

 the Cincinnati district. PIcurograptus linearis, which is so important 

 a fossil in northern Europe, is in this country known only from a single 

 specimen found at Holland Patent. CaUograptus covipactus is also 

 known only from Holland Patent. There are varieties of Dicrauo- 

 graptus nicholsoni in older shales, but the typical form is restricted to 

 the horizon of the Utica of Holland Patent. It is found also in the 

 Fulton shale of the Cincinnati district and near Saratoga. In at- 

 tempting a correlation of any other fauna with that of the typical 

 Utica it must be borne in mind that some of the typical species of that 

 fauna are so rare that but few specimens are known. Practically all 

 the species of graptolites which are not restricted to the locality at 

 Holland Patent are species bf considerable vertical range. The 

 occurrence, however, of Pleurograptus linearis stamps that fauna as 

 younger than that with Dicranograptus clingani and probably equiva- 

 lent to the upper Chasmops shale of Sweden. 



The Fulton shale at the base of the Eden at Cincinnati contains a 

 graptolite fauna very like that at Holland Patent. Some of the 

 species are : — 



Mastigograptus toiuiramosus Climacograptus typicalis Hall, 



(Walcott), C. putilhis (Hall), 



Leptograptus annecians Walcott, Lasiograptus himucronatus tivii- 

 Dicranograptus nieholsoni Hop- dus Ruedemann. 



kinson, 



Associated with these are Cri/ptolithus tessellatus and Triarthrus 

 becki. In higher beds of the Eden of the same region one finds Dictyo- 

 neina arbuscula Ulrich, Mastigograptus gracillimus (Lesquereux), 

 Chaunograptus gemmatus Ruedemann, and Climacograptus typicalis 

 Hall. 



From the above we may derive that the more widespread species 

 of the Typical Utica {Pleurograptus linearis fauna) are Mastigograptus 

 tenuiramosus, Leptograptus annectans, Lasiograptus himucronatus 

 timidus, and Cryptolithus tessellatus. Climacograptus typicalis, Dicran- 

 ograptus nicholsoni, and Triarthrus becki are also species which though 

 not strictly restricted to the Utica, are to be found in every outcrop 

 of that formation. 



From the above it is evident that while some of the graptolites have 

 a long range in the black shales of New York, there are species which 

 seem to be characteristic of certain horizons. Thus we have in the 



