GRAPTOLITES OF NEW YORK, PART 2 



425 



longitudinal sections [for instance 1893, pi. r, fig. 7, 8] demonstrate, how- 

 ever, that the distal ventral margins of the thecae were slightly directed 

 inward and the thecal tubes slightly wider in the middle than at either mil. 

 The same is seen in the figure here given, but the main inflation in our 

 material takes place in lateral direction, as the frontal view (text fig. 387 | of 

 a rhabdosome shows. This lateral inflation gives a bottle-shaped appearance 

 to the frontal view of the distal parts of the thecae. It is probable that 

 this is an extreme development of a feature of C . scalaris and of varietal 

 character, the importance of which can not be determined until the periderm 

 itself is observed. 1 



Aside from these intermittent inflations, the transverse sections of the 

 rhabdosome are considerably less rounded and more rectangular than those 

 figured by Tornquist [see text fig. ^7\- It is hence for the present safer to 

 separate this form at least varietally from Hisinger's type. In general 

 form, curvature and closeness of arrangement of thecae, the specimens 

 from Maine agree well with the Swedish types. Their rhabdosomes do not 

 reach the length of the latter, a difference quite probably due to the 

 fragmentarv character of the material. 2 



The septal suture is in the Maine specimens subject to extreme vari- 

 ation ; it is rigidly straight in some (or the most) and in others as extremely 

 zigzagged as in C. s c h a r e n be r g i . Between the two extremes are 

 found various transitions and in some cases the same suture is partly straight 

 and partly zigzagged. Those with strongly zigzagged sutures are rela- 

 tively wider and shorter, but since they lie parallel to the others, their 

 present form can not be due to secondary shortening within the rock. 



Hall has referred a number of specimens from the Utica shale of the 

 West Canada creek and the Normanskill shale near Albany, showing only 

 the scalariform frontal aspect, to Graptolithus scalaris Linne. 



1 The maximum lateral inflation occurs exactly where the new theca buds and both 

 features are obviously connected causally. 



2 In its dimensions this variety is most suggestive of the variety m i s er ab i 1 i s since 

 described by Elles and Wood. 



