GRAPTOLITES OF NEW YOHK, PAUT 1 629 



order), which equal the primary in length and width, diverge under angles 



of 120° to 150°; the four principal stems describe a zigzag line, the sections 



of which form an angle of 150°. The undivided denticulate branches 



stand at nearly right angles to the general direction of the principal 



stems. The thecae of the branches are tubular, narrow, about 2 mm long, 



three times as long as wide, one 



fourth to one third of their length 



in contact, numbering 8 in 10 mm, 



their outer margins nearly straight 



or slightly concave, the apertural 



margin straight and at right angles 



to the axis of the theca, inclined 



10° to the axis of the branch. Total 



number of branches 40 or more; 



their length at maturity 30 mm or Fig. u Gomogrraptus geometricus sp. nov. 



Further enlar(?ement of the specimen reproduced on 

 mnrp ripnfTal flieV nr>+ nKaorTrprl P'*'*^ 7, flprure 12 to show the thecae forming the 



UlOlti. ^^eniiai UISK not OOServea. branches of the first, second and third orders. Deep 



Jr^osiUon and localtties. Extremely 

 common at the Deep kill in a layer of the horizon with Didymograptus 

 b i f i d u 8 , but already beginning in the preceding horizon. 



Remarhs. This species is closely related to the preceding one which 

 occurs in the underlying horizon, dijffers, however, from it by the shorter 

 length of the sicula and thecae, the very different angle of divergence 

 and more compact arrangement of the branches. By the greater angularity 



of the zigzag shaped 

 principal stems, it 



Fig 45 Gonlograptus geometricus sp. nov. Fragment of a branch. resemblCS morC the 

 Deep klU. X5.25 . . . 



type species oi the 

 genus than the foregoing species; but, like the latter, it differs from 

 that species by the subapical budding point of the primary thecae at the 

 sicula. 



I have little doubt that the specimen on which Hall based his species, 

 Thamnograptus anna, was a branch of this or a very similar 



