546 



NEW YORK STATE MUSEUM 



Canada. The other is also found in Lower Canada viz, D. foliaceus 

 var. i n c i s u s . 



The relationship of all these forms to Diplo. prist is Hisinger is 

 very close. Indeed we may yet have to return to Hall's first view and 



make D. foliaceus a variety of D . p r i s t i s. 

 The Swedish forms of D . p r i s t i s are preserved 

 in demirelief and in different rock to our British 

 graptolite bearing sediments but in the present 

 Y state of our knowledge I should probably place 

 ^w? their D . p r i s t i s if I found it here as a variety 

 of D . foliaceus. 



Professor Lapworth has added to his manu- 

 script report rubbings of camera drawings of typical 

 specimens of the two varieties of D . foliaceus, 

 which he found in the Stockport collection. By 

 means of these it has been an easy task for the 

 writer to recognize the two types in the collec- 

 tions from the outcrops of Normanskill shale in 

 the State and to establish the fact of their 

 presence in all the more important ones. The 

 actual constancy of the differences is guaranteed 

 by the fact that the slabs will usually contain the 



Fig. 279-82 D i p 1 o g r a p t u s- Fig. 



!nh?s P ^fe^^u U /" of'?h r e ap Fim rhabdosomes of but one of them, often in great 



Survey. Fig. 280 Hall's figure of 



Dipiograptus pristis in Pa>- numbers and that the two are not found on the 



N. Y. vol. 3. r lg. 281 Dipiograp- 

 tus foliaceus from Murchison's 111 ■ j J ,«.1 «. **. 11 



locality (x 6jo.. Fig. 282 _ d i p i o - same sy nrhabdosome or so associated that it would 



graptus pristis from Hisinger's lo- J 



■^l^±J^tfJ^^Tl%^l become probable that they grew as parts of one 

 synrhabdosome. 



We insert here Lapworth's descriptions of the two varieties with a few 

 alterations made to attain uniformity, adding such observations as are per- 

 mitted by the larger collections which we have at our disposal. Besides 

 these two, several more varieties or rather mutations had to be recognized, 

 whose descriptions follow. 



