GRAPTOLITES OF NEW YORK, PART 2 



327 



the)' are seen to begin to curve gently inward and approach again at an 

 approximate distance of 150 mm from the point of bifurcation. 



The length of the sicula has not been observed, but a short, stiff 

 virgella is nearly always present. The first two thecae bear curved lateral 

 spines at the points of flexure. The first two pairs of thecae grow in alter- 

 nate arrangement, the following in single series separated 

 by a septum. The thecae number 8 to 10 in 10 mm (20— 

 25 in 1 inch), are 1.8 mm long, and overlap one half their 

 length ; their ventral walls are gently convex, the apertural 

 parts strongly introverted and introtorted, contained in and 

 apparently nearly entirely filling round excavations that 

 occupy one third the width of the branch and equal in 

 length more than one half the free part of the thecae. 



Position and localities. D. ramosus is common in 

 the Normanskill shale at Kenwood and Stockport ; it also 

 occurs in the same horizon at the Moordener kill, at Mt 

 Moreno and at several localities about Troy (as at Mt 

 Olympus). In several outcrops, as those of Glenmont 

 and Mt Moreno, it is very rare and replaced by varieties ri g . 255,256 d; c ran o- 



J L J grapt us ramosus 



which occur there profusely. It does not seem here to portion ofk ?habdosome 



showing the sicula and 



go in its typical form above the Normanskill shale. Gur- pt^N. ( y 5 o^inli^i 



1( - ~ii* i l i i National Museum). Fig. 



ley 1806, p. 71 claims to have observed a much more 256 co Py of Hairs figure 



J L s 1 ' J 111 Decade II [pi. A, fig. 



ki • , • .1 t t T~v - 11 . 20]. See also text fitiure 



nder variety in the Upper Dicellograptus zone at 4I 



Magog, Quebec, while Whitfield [1877, /or. cit.\ and Gurley have cited it 

 from the Utica shale of the Mohawk valley. The Mohawk valley speci- 

 mens were stated by Whitfield to have come from Oxtungo creek. Slabs 

 from that locality covered with specimens of a Dicranograptus are preserved 

 in the State Museum but the latter prove to belong to a spinose mutation 

 [see below]. Freeh [1877, p. 616] has cited it also from Saratoga lake in 

 New York. The only form known to the writer from that locality is D . 

 nicholsoni. D. ramosus has also been found in the Normanskill 

 shale of New Jersey by Weller and has been early recognized by Lapworth 



