GRAPTOLITES OF NEW YORK, PART 2 



a Diplograptus euglyphus Lapworth var. pygmaeus nov. 



371 



Plate 25, figure 24 



Description. Synrhabdosome attaining- a diameter of 40+ mm and 

 composed of 9+ rhabdosomes. Rhabdosome small (average length 10 

 mm, maximum length observed 21 mm), narrow (width usually but .9 mm, 

 rising to 1.4 mm), of uniform width. Sicular extremity furnished with 

 short, thin virgella and two equally unconspicuous lateral spines. Sicula not 

 observed. Nemacaulus thin, rarely protruding from antisicular end and 

 then but for a very short distance. Thecae very closely arranged, 

 numbering 14 to 15 in 10 mm (34-38 to the inch), overlapping not 

 quite one third of their length, inclined at an angle of 30 to 40 ; 

 outer margin first straight or slightly concave (by depression of the 

 wall), and then convex ; aperture normal to axis of theca, apertural 

 margin straight to slightly concave. Interthecal excavation deep 

 (two fifths of width) and half as long as denticle. No septal 

 grooves observed. 



Position and locality. This species was found to be 

 very common in a layer in the Normanskill shale at the 

 power house north of Lansingburg, Rensselaer co., N. Y. 



Remarks. The present type is in most characters a 

 smaller edition of D . e u g 1 y p h u s , with which it has the 

 outline of the thecae in common. From other small forms v - 



riff. 317, 318 Diplo- 



it is easily distinguished by the combination of the shape ™ r - pygmalus^Fig! 



1 3*7 Portion of typical 



of the thecae and their close arrangement. Only one frag- Yo^mgTh'Xdosomi. 1*1 

 mentary synrhabdosome [pi. 25, fig. 24] was observed. Though this variety 

 has been found in but one layer, it occurs there to almost the exclusion of 

 other forms (Climacogr. parvus and D i p 1 o g r . f o 1 i a c e u s the 

 only other associates) and with great uniformity of characters. 

 The absence of free nemacauli is a noteworthy feature. 



