534 NEW YORK STATE MUSEUM 



corresponds with the Middleville specimens of D i p 1 o g r a p • 

 tus amplexicaulis^ with which it was compared. 



Station 23. Fitzgerald's quarry, Port Schuyler 



In James Fitzgerald's quarry (station 23) f of a mile south of 

 the arsenal, at the western terminus of Fourth street in Port 

 Schuyler, thick bedded gray and black argillaceous shales and 

 arenaceous, mica-bearing argillite are broken for road metal. 

 The sandy beds contained: 



Schizocrinus nodosus, Hall 



Dalmanella testudinaria, Emmons sp. 



Plectorthis plicatella, Hall 



Platystrophia biforata, SchlotJieim ep. ' 



Plectamboinites sericea, Sowerhy sp. ^ 



Rafinesquina alternata, Conrad sp. 



^Diplogaptus amplexicaulis was first described by Hall from 

 the middle Trenton of Trenton Falls and Middleville. There, as well as 

 at Trenton, it occurs in great profusion in certain beds of the middle 

 Trenton, while in the Rathbone brook section, south of Trenton Falls, it 

 was also observed in beds considered as lower Trenton by Dr Th. A. 

 White (51:86). Whitfield, as observed (p. 496) found it at the Watervliet 

 arsenal and at south Troy, and based on it his correlation of these 

 Bhales with the Trenton. Gurley, who considers it as only a mutation 

 of D. f 1 i a c e u s, assigns it to the Chazy (Mystic, Can.) and 

 Trenton. Joseph F. James records its collection in the typical Maquoketa 

 locality (Amer. geol. 4:237); Walcott mentions its being found in the upper 

 part of the Lorraine section (36a:339); and Whitfield enumerates in 

 his catalogue (61:20-21) asD. amplexicaulis a number of Hall's 

 types of G r. p r i s t i s of Pal. N. 7., v. 1, from Turin, Lorraine, CoUins- 

 Tille and the Oxtungo creek. It becomes apparent from these citations 

 that this graptolite is of rather uncertain value as an index fossil of the 

 Trenton; it has been reported from beds ranging from the Chazy to the 

 Lorraine, and probably the form is not yet well understood or D. f o 1 i- 

 a e e u s, to which it is closely related, has been mistaken for it. The 

 amplexicaulity of the thecae is not restricted to this species, the conca^o- 

 <;onvex section of the rhabdosome is not observable in flattened specimens, 

 so that in the determination of specimens from the shale one is restricted 

 to the observation of the dimensions, outline of thecae and rhabdosome, 

 and of the general habit. These characters, however, being subject to 

 Alteration by variations in pressure, are often difficult of exact observation. 

 The relations of this form to D. f o 1 i a c e u s and its vertical range 

 apparently need farther study. The writer has not seen typical speci- 

 mens of this form from beds of younger than middle Trenton age. 



