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[Senate 



GRAPTOLITHUS WHITFIELDI (n. s.)- 



Stipe simple, flat, gradually expanding from the base to near the middle of its 

 length, the upper part gradually narrowing in the direction of the apex, rarely 

 continuing of the same width above the middle: serratures shallow, angular; 

 the upper margin of the denticles short and nearly rectangular to the axis, the 

 lower side twice as long as the upper, the tips furnished with mucronate or short 

 setiform extensions which project in a line with the upper margin of the den- 

 ticle. Serratures twenty-two to twenty-eight in the space of an inch. 



Length from one inch to an inch and a half. 



This species has the general form and proportions of the G. pristis (Hall, Pal. 

 New-York, Vol. i, pa. 265, pi. 72, f. 1); but that species does not contract its 

 width towards the upper extremity, the denticles are concave above, and the points 

 directed upwards. The form of the serratures and denticles is quite different in 

 the two species, and the setiform processes are never observed on that species as in 

 this one, where it is a constant feature. 



The present form is not unlike the one described as G. 

 mucronatus (Hall, Pal. New-York, Vol. i, pa. 268, pi. 73, 

 f. 1) ; but that species has differently formed serratures and 

 denticles, and the entire stipe is more lax. The upper mar- 

 gins of the denticles are traceable nearly to the midrib in 

 well-marked specimens of that species, and the mucronate 

 tips appear to be formed by the gradual narrowing and ex- 

 tension of the substance of the denticle; while in this one, 

 it is an abrupt extension from the apex of the denticle. 



For the purpose of comparison with the G. pristis, I have 

 presented figures of the two species, which are enlarged to 

 twice the natural size. 



These specimens are from the same locality, and the differ- 

 ences are constant. 



Fig. 1. G. WHITFIELDI. Fig. 2. G. pkistis. 



Geological position and locality. In the shales of the Hudson river group : Near 

 Albany. 



GRAPTOLITUS SPINULOSUS (n.s.). 



Stipe simple, flat; sides subparallel, gradually expanding from the base, which is 

 furnished with several minute setiform radicles: serratures not distinct, the mar- 

 gin sinuous, the prominent parts extended into slender ascending spinuliform 

 processes. These spinules are about one-sixteenth of an inch distant from each 

 other. 



