CYRTOrxRArTITS. 



507 



Welsh Border : Pencerrig, near Builth ; Trecoed, near Builtli ; Llanelwedd 

 Quarry, near Biiiltli. Lake District: Cross Haw Beck, Sedbergh; Stockdalc ; 

 Nanny Lane, Troutbeck. S. Scotland: Riccarton. A^. Wales: Penarth Quarry, 

 Carrog ; Benarth Shore, Conway ; Rose Mill Farm, Conway ; Tarannon River. 



Associates, etc. — Gifrtog. Murchisoni is a very abundant fossil at the base o£ the 

 Wenlock Shale and its equivalents ; it is commonly associated with Monog. priodov, 

 M. vomerinus, and Ret. {Gladiog.) Geinitzianus. 



Collections. — Geological Survey of England and Wales, British Museum of 

 Natural History, Sedgwick Museum, Lapworth, and the Authors. 



Cyrtograptus Lundgreni, Tullberg. Plate LII, figs. 1 a—d. 



1883. Cyrtograptus Lundgreni, Tullberg, Skanes G-rapt., ii, p. 36, pi. iii, figs. 8—11. 

 1900. Cijrtograptus Lundgreni, Elles, Quart. Jouru. Geol. Soc, vol. Ivi, pi. xxiv, figs. 1 a, b, text- 

 figs. 24 a, h. 



Stipe of polypary slender and sub-circular, with several somewhat stiff cladia 

 radiating from the convex margin. Thec« ten in 10 mm., of the general 

 type of M. spiralis, but much smaller; those of the cladia numbering eight 

 in 10 mm., more tubular, and overlapping fully one-half their extent. 



Description. — The stipe of the polypary is sub- 

 circular in form and is slender, not exceeding 1 mm. 

 in breadth, the actual proximal end being unknown ; 

 there is, however, no indication of any spiral enroll- 

 ing. 



The thecse of the stipe are for the most part 

 sub-triangular, with reflexed apertural margins, but 

 they acquire a more tubular character with tlie 

 diminishing curvature of the stipe, and the amount 

 of overlap increases simultaneously ; so that at the 

 termination of the polypary the thecse overlap from 

 one-third to one-half their length and are distinctly 

 tubular in form. All the thecse of the cladia are of 

 the same type as those of the termination of the 

 stipe. It is possible that the apparent difference is 

 somewhat exaggerated by the variation in curva- 

 ture, for when the thecse appear sub-triangular they 

 are always on the convex side of the curve ; but both at the distal termination 

 of the main stipe and on the cladia they are on the concave side and are therefore 

 compressed rather than stretched, so that they naturally overlap more. This 

 circumstance is no doubt largely, though not wholly, responsible for the different 



Figs. 353 a and b.—Cyrtograpt 



us Lund- 



greni, Tullberg. 



^ 



'•■ja i 



>S1 '4: 



'V <Si 





f 1 





> f 





a. Thecffi of the proximal part of the 

 stipe. Enlargement of part of PI 

 LII, fig-. 1 h. 



h. Thecse of one of the cladia. 

 Llwynrhedith Quarry, Long Moiin- 

 tain ; Wenlock Shales. Coll. Elles. 



