GRAPTOLITES OF NEW YORK, PART 2 419 



suspecting that this group existed already in the Appalachian (Levis) basin 



before Trenton time, lor the form from the third Deepkill /one described 

 in Memoir 7 as C. pungens is so much alike in general form and size, 

 in shape and closeness of arrangement of thecae to C. p u t i 1 1 u s and 

 Dipl. tereti us cuius [see especially ibid. pi. 16, fig. t c> | that it can be 

 fairly assumed that better material will show its close relationship to these 

 species, and its horizon also corresponds to that containing 1 ) . tereti u s- 

 cuius in Europe. It can therefore be considered as a vicarious form of 

 that European species and may eventually be shown to be the progenitor of 

 C . putillus. 



In regard to the latter relationship a small feature is of great interest 

 which I had occasion to observe in the beautifully preserved specimens of 

 the Ulrich collection. This is the presence of minute mucros [see text 

 fig. 369] at- the point of abrupt widening of the thecae just above the aper- 

 tural notches. These mucros correspond to similar, longer spines of C. 

 pungens [see Mem. 7, pi. 16, fig. 14]. 



In the compressed state it is very difficult to distinguish the rhabclo- 

 sorae of C. putillus from the young rhabdosome of its associate C. 

 typical is, which beginning very narrow and widening slowly, presents 

 a strikingly like aspect. The slightly greater length of the thecae of 

 C. typical is will serve as a distinguishing character where both are 

 commingled [compare fig. 361 and fig. 375]. 



This species is also related to C. innotatus Nicholson, a consid- 

 erably younger form (Llandovery, Middle Birkhill) with which it has the 

 dimensions and character of thecae in common. It is especially interesting 

 to note that the later innotatus possesses long mesial spines on the 

 lower outer corners of the free walls, where C . putillus and C . t y p i- 

 cal i s develop mucros. It may for this reason be considered as a paracmic 

 form of the C . typicalis-putillus race. 



