GRAPTOLITES OF NEW YORK, PART 2 



2 39 



Hopkinson's elaborate description as traversing the rhabdosome throughout 

 its length, are the partition walls between the thecal cavities compressed or 

 projected into one plane. 



The "bulbous expansion" is caused by the abrupt divergence of the 

 last portions of the thecae. 



The slender form and the divergence of the thecae near the aperture 

 are characters which readily distinguish this form from its congeners. 



Corynoides gracilis Hopkinson mut. perungulatus nov. 



Plate 13, figures 3, 9, 10, ir, 13, 14 



Description. Rhabdosome relatively long (10-12 mm), narrow (.5- 

 .85 mm), straight, of uniform width and 

 rigid appearance, consisting of a sicula 

 and three thecae. Sicula long (2.4 mm) 

 and thin, with circular and unprotected 

 aperture. Thecae very slender, hardly 

 widening in apertural direction, not 

 divergent from the sicula. Aperture 

 straight, normal to the axis of the theca. 

 Distal extremity of the mature rhabdo- 

 some furnished with three clawlike spines 

 which project upon a tonguelike process. 

 Nema very thin and filiform. 



Position and localities. This muta- 

 tion is a very abundant form in the Nor- 



manskill shales ( Dicellooraptus zone) at 



v 136 137 138 139 



Glenmont, Albany co., but has also been Fi g . i 3 6- 39 corynoides gracilis mut. pemn- 



gulatus nov. Fig. 136, 137 Specimens showing die 



nlrjprvprl in a fpw ntlipr InrnlitlVc in Hip sicula and apertural spines. Fig. 138 Fragmentary speci- 



OUSerVCU 111 a ieW OUier lOCaillieS, 111 CUC men showing the oldest fheca. Fig. 139 Sicula. The 



. originals from the Normanskill shale at Glenmont and en- 



same horizon, as at Mount Moreno near iar g edx 7 



Hudson and Speigletown, north of Troy. It also seems to occur in 



homotaxial beds in Arkansas. 



Remarks. From the other species of Corynoides this one is easily dis- 

 tinguished by its slender, straight form. Its most striking feature is the 



