DIPLOGRAPTUS. 231 



Var. penna, Hopk. Plate XXVIII, figs. 9 a—c. 



1809. Diplograpsus penna, Hopkinsou, Journ. Quekett Micros. Club, vol. i, p. 159, pi. viii, fig. 12. 

 1872. Diplograptus penna, Hopkinsou, G-eol. Mag., vol. ix, p. 505, pi. xii, fig. 0. 



In addition to the typical form of 0. vesieulosus there occurs on the same horizon 

 a closely allied, though smaller and narrower form, which appears to be that 

 originally described by Hopkinsou as Diplog . penna. We believe it to be a variety 

 of 0. vesieulosus. 



This variety rarely measures more than 3 cm. in length, and seems never to 

 exceed 2'5 mm. in breadth, while the vesicle is commonly thinner and more dilated 

 nearer to its distal extremity than is the case in the typical form. The thecal are 

 practically identical with those of 0. vesieulosus. 



Horizon and Localities. — Llandovery (Birkhill Shales) (zone of 0. vcsieidosus). 



S. Scotland: Frenchland Burn; Dobb's Linn; Belcraig. Lake District: 

 Skelgill ; Keisley. 



Associates, etc. — Var. prima occurs somewhat sparingly in S. Scotland with the 

 same associates as the typical species ; it occurs, however, in some abundance at 

 Keisley, where it has been fonnd by Dr. Marr associated with Dimorphog. confertus. 



Collections. — Marr, Sedgwick Museum, and the Authors. 



Diplograptus (Orthograptus) bellulus, Tornquist. Plate XXIX, figs. 2 a — e. 



1890. Biplocjraptus bellulus, Tomquist, Siljansoinr. Graptol., Acta Univ. Lund., vol. xxvi, p. 28, pi. 



i, figs. 25—29. 

 1893. Diplograptus bellulus, Tomquist, Structure Diprionidre, Acta Univ. Lund., vol. xxix, p. 10, figs. 



42—44. 

 1897. Diplograptus bellulus, Tomquist, Diplog. and Heteroprionida? of Scauian Rastrites Beds, Kongl. 



Fysiogr. Siillsk. i Lund Handl., vol. viii, p. 17, pi. ii, figs. 20 — 25. 



Polypary short and somewhat robust, not exceeding 2 cm. in length, and 



widening quickly to its maximum breadth of 2 mm. Sicula small, with 



very long virgella 8 mm. in extent. No septum. Thecas fourteen to ten 



in 10 mm., walls showing slight sigmoid curvature in subprofile view, having 



a length of 2 mm., and overlapping one half their extent; apertural margins 



slightly undulate, wide. 



Description.- — The polypary shows an unusual degree of concavo-convexity for 



this group, and is short and distinctly wide for its length, which rarely exceeds 



1*5 cm., and widens quickly from '8 mm. to its maximum breadth of 2 mm. 



(relief). The sicula does not measure more than *5 mm., but the virgella 



