GRAPTOLITES OF NEW YORK, PART 2 369 



apparently become widely separated. In this excavation of the thecae it 



much resembles L). f o 1 i a c e u s van acutus, with which it has also the 

 number of thecae in a certain space in common. Its smaller and more 

 nearly uniform width and the mostly convex aperture permit, however, of 

 easy separation from that form, though a close relationship between the two 

 is very probable. 



Another species, which it approaches in the form of its thecae is I), 

 euglyphus; which has a like deep excavation of the proximal part of 

 the theca. From this again it can be distinguished by the different num- 

 ber of thecae in a certain space, D. euglyphus having a much looser 

 arrangement of the thecae. 



Diplograptus (Glyptograptus) euglyphus Lapworth 



Plate 25, figures 21-23 



Diplograptus dentatus (Brongniart) Lapworth. Belfast Nat. Field Club Rep 't 



& Proc. v. 1. pt 4, apx. 1877, p. 132. pi. 6, fig. 13 

 Diplograptus dentatus Lapworth. Geol. Soc. Quar. Jour. 1878. v. 34 

 Diplograptus dentatus Lapworth. Ann. & Mag. Nat. Hist. Ser. 5. 1879. 



4:424 

 Diplograptus (Glyptograptus) euglyphus Lapworth. Ann. & Mag. Nat. 



Hist. Ser. 5. 1880. 5:166, pi. 4, fig. i4a-e 

 Diplograptus euglyphus Lapworth. Ann. & Mag. Nat. Hist. Ser. 5. 1880. 



6:21 

 Diplograptus euglyphus Lapworth. Can. Geol. Sur. Rep't, 1887-88, 1889. 



Ser. 2. v. 3, pt 1, p. 95 B 

 Diplograptus euglyphus Lapworth. Roy. Soc. Can. Proc. & Trans. 1887. 



4:177ft' 

 Diplograptus euglyphus Gurley. Jour. Geol. 1896. 4:298 



Description. Synrhabdosome not observed. Rhabdosome long and 

 narrow (40+ mm long and 1.4 mm— 2.2 mm wide in mature parts), of 

 uniform width (attaining its full width within 5 mm— 10 mm). Sicular 

 extremity furnished with minute virgella and rarely two thin curved lateral 

 spines. Sicula not observed. Nemacaulus very thin, but attaining con- 

 siderable length. Thecae numbering 7 to 9 in 10 mm (18-22 to the inch). 



