GRAPTOLITES OF NEW XOUK, I'AKT 1 



605 



Remarhs. The fact that the rhabdosoraes of this species in the usually 

 compressed state [fig.20] appear to be derived from a flabelliform colony, led 

 to the early view that these organisms had been tiabelliforni, like gorgonias. 

 Brogger was able to show for D. flabelliform e that its rhabdosome 

 was actually funnel-shaped, by finding specimens where the upper and lower 

 parts of the rhabdosome ai-e not lying in the same bedding plane and are 

 separated by a thin layer of shale \loc. cit. tab.l2, fig.lSj. Such specimens 

 have been also found among the Schaghticoke material, where the upper 

 half is partly broken away and the loAver half is exposed in its place. 

 The early growth stages, and specially such obliquely compressed specimens 

 as those figui'ed on plate 1, figures 16-19, leave no doubt that a cup-shaped 

 arrangement of the branches took place from the beginning. 



Br<)gger desci'ibes a variet}' of D . f 1 a b e 1 1 i f o r m e as var. c o n • 

 fertum Linnarsson ms. and a mutation, D. f 1 ab e 1 1 i f or m e mut. 

 n o r V e g i c u m ( D . n o r v e g i c ii m Kjerulf). The variety confer turn 

 is said to have a much finer and closer network, and its transverse dis- 

 sepiments remain always very thin. The mutation n o r v e g i c u m is 

 characterized by short angular meshes and thick dissepiments. It occurs at 

 Vakkero near Christiania in a higher bed than the typical form. Matthew 

 records [1892, p.36] that the variety confer tum appears to be particularly 

 common in the lower beds at St John containing Dictyonema, and adds that 

 it is distinguished from the typical form, found at a higher level, by its 

 vasiform shape. The same author also refers a form which he found 

 in the middle and upper Dictyonema bed with some doubt to 

 D . n r V e g i c u m ; and describes the principal form of St John as 

 var. a c a d i c u m , stating that it differs from the typical Swedish D . f 1 a - 

 bell if or me by having more numerous thecae on its branches, namely 16 

 to 17 in 10 mm against 10 to 15 of the typical form. 



As Brogger suggests it is questionable, on account of the great multi 

 plicity of variations and transitions, whether these varieties can be kept apart. 

 This has also been the experience of the writer with the New York material. 

 In this, fragments bearing the characters of c o n f e i- 1 u m and nor- 



