GRAPTOLITES OF NEW YORK, PART 1 473 



extremity of the stipes with the smaller cells, was the younger one, and 

 recognized two subdivisions, namely Monoprion, with a single row of cells, 

 and Diprion, with a double row. As we shall see later on, nearly all 

 of these opinions of the pioneer have been greatly modified. Indeed, only 

 a year after the publication of Barrande's work, Scharenberg [1851] in 

 Norway, corrected some of Barrande's conclusions, without however finding 

 direct followers. He claimed that the division into Monoprion and Diprion 

 excludes the branching forms, that in Diprion there are not two independent 

 series of cells, but the latter alternate without exception, and he also asserted 

 that the narrower extremity is not necessarily the younger. 



Hall adopted Barrande's views as to the presence of a solid axis in all forms 

 and as to that of one or two common canals, in Monoprion and Diprion respect- 

 ively. He retained however all forms in the genus Graptolithus, on account of 

 the discovery of forms, as Gr. r a m o s u s, which show " the occuiTence of both 

 a single and a double series of cellules upon the same stipe " \lor. rif. p. 40]. 

 He also considered the use of the terms Tetragraptus and Dichograptus imprac- 

 tible, as for the most part only fragments of stipes are found, which would not 

 allow these distinctions. At the same time his material was the first to exhibit 

 the multiplicity and complexity of foiins of branching gi-aptolites, which soon 

 led to such an extended subdivision of these branching forms that it is now 

 claimed [see Freeh] to have gone beyond the proper limits. 



Hall also made important additions to our knowledge of the central or 

 basal portions of the colonies. These were the recognition of an initial 

 process in many forms, which he termed the " radicle" or "initial point" and 

 considered the beginning of the solid axis. It is now, under the tenu 

 " sicula " introduced by Lapworth, known as the mother theca of the colonies. 

 Scharenberg and Richter had also pointed out the presence of this organ, the 

 latter calling it the " Fuss." 



Hall further concluded that there is in the branching forms a central con- 

 necting process, which he thought to be always destitute of celh'les and for 

 which he introduced the term " f unicle." The opinion concerning the presence 



