352 NEW YORK STATE MUSEUM 



had he had access to Lapworth's figure. While these varieties of D . 

 foliaceus upon close comparison may be hardly or not at all distin- 

 guishable, the fact remains that they appear in widely separated regions 

 or basins and seem to be absent in intermediate areas as in the east of 

 North America. They might therefore represent independently developed 

 varieties whose deceptive uniting would lead to wrong inferences. 



d Diplograptus foliaceus var. alabamensis no v. 



Plate 25, figure 3 



Description. Rhabdosome long and slender, attaining a length of 

 35+ mm and a width of 1.5-2 mm; beginning with a narrow sicular end, 

 .8 mm wide and increasing slowly in width, attaining its full width in about 

 10 mm. Sicular end marked by small virgella and lateral spines. Free 

 nemacaulus not observed. Thecae numbering 9 to 11 in 10 mm ; with con- 

 vex ventral and horizontal or slightly inclined apertural margins, overlapping 

 one half of length, inclined at angle of 45 . 



Position and locality. In the calcareous Trenton shales of Pratt's 

 Ferry, Bibb co., Ala. 



Remarks. This, the only representative of Diplograptus in the suite 

 of graptolites from the Trenton shales of Alabama, differs from the material 

 obtained in our State, by its remarkable slenderness. In this and the form 

 of the thecae in the usual state of preservation, it recalls D. a n g u s t i- 

 folius, but differs from that species in the form of the rhabdosome (more 

 gradual widening) and looser arrangement of thecae. Still, it could per- 

 haps with equal propriety be referred to that species as a variety and seems 

 to stand in its character between a narrow D . foliaceus var. incisus 

 and D. a n g u s t i f o 1 i u s. From D. eu glyph us it is easily distin- 

 guished by the much shorter interthecal excavations. 



e Diplograptus foliaceus unit, vespertinus now 



Plate 25. figures 4, 5 



Diplograptus pristis (parte) Hall. Pal. N. Y. 1847. v. 1, pi. ;_\ fig. 1, ia, 

 ib, ik, il 



Description. Synrhabdosome not observed. Rhabdosomes .is a rule 



short (15 mm, greatest length observed 42 mm), widening gradually from 



