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NEW YORK STATE MUSEUM 



little rhabclosome a perfect network, recalling in form the veination of a 

 leaf, or whether they are the remains of long conical or tubular capsules like 

 the appendages of Mastigograptus tenuiramosus is unfortunately 

 left uncertain by the material. 



Ptilograptus poctai sp. now 



Plate t, figure 8 



Description. Rhabclosome of unknown size ; fragment 10 mm long, 

 consisting of flatly zigzagged stem and closely arranged (5 in 5 mm) 

 obliquely ascending (50 ), somewhat flexuous branches which are 7+ mm 

 long and .3 mm thick. Stem and branches distinctly composed of slender 



thecae which strongly project from the branch 

 (angle of inclination 30"), are four times as long 

 as wide, overlap a little more than one fourth 

 their length and number 12 in 10 mm. Their 

 ventral margin is straight, the apertural margin 

 slightly concave and normal to the axis of the 

 theca. From its ventral rim a tonguelike, termi- 

 nally notched process proceeds that is about half 

 as long as the theca ; sicula and basis have not 

 been observed. 



Position and locality. A single specimen has 

 been found in the Normanskill shale at Glenmont, Albany co., X. Y. 

 where it is associated with D i c r a n o g r. nicholsoni var. di a p as o n. 

 Remarks. From the species of Ptilograptus which we have recorded 

 from the Deepkill shale, this type is easily distinguished. It stands in the 

 middle between P . p 1 u m osu s and P . ge i n i t z i a n us in thickness and 

 size of branches and differs markedly from both by the prominent denticles 

 and the apertural processes of its thecae. Its strong denticulations it has 

 in common with P. acutus Hopk., a form of the Welsh Lower Llandeilo, 

 which has received its name from its acutely pointed denticles. It resem- 

 bles the latter form also in its habit, as far as the fragmentary character o( 

 our specimen permits to judge, but is of smaller size and more delicately 



poctai 



Fig. 53 Ptilograptus 

 sp. nov. Enlargement (x 5) of type 

 specimen 



