332 



BRITISH GRAPTOLITER. 



Q > 



xtf'l 



Tiffin 





netting often shown in the exterior parts of the lacinia in other species, there is an 

 irregular pnter fringe having a somewhat ragged and spinous appearance. 



In the scalariform view, the 



Figs. 218 a and I.— Newograptuafibrcetw (Lapw.). SCOpulate processes are Well sllOWll, 



each originating directly from one 

 of the septal strands. They occur 

 in pairs. The earlier or stem-like 

 portion of each is at first hori- 

 zontal, and is afterwards bent into 

 a curve, the convex side being up- 

 wards. At a distance about equal 

 to the diameter of the thecal portion 

 of the polypary, it branches dicho- 

 tomously, and the branches divide 

 into branchlets in their turn; traces 

 of an exceedingly thin membrane, 

 which once probably connected 

 the branches and branchlets, are 

 occasionally discernible. 



The thecse are alternate in their arrangement and strikingly recall those of 

 Hallog. mucronatus. 



Affinities. — N. fibratus resembles closely Neurog. margaritatus, from which it 

 differs chiefly in being a larger form, in having a stronger and more fibrous 

 nature, a more attenuated test, and also scopulate septal processes. 

 Horizon and Localities. — Bala, Hartfell Shales. 

 S.Scotland: Hartfell; Dobb's Linn ; etc. Ireland: Carnalea. 

 Associates, etc. — Neurog. fihratus occurs in the Lower Hartfell Shales in the 

 zones of Dicranog. Clingaui and Pleurog. linearis. It is found at the lower horizon 

 associated with Dicellog. Morrisi and Dicranog. ramosus, and at the higher horizon 

 with Pleurog. linearis and Orthog. truncatus var. pauperatus. 



Collections. — Geological Survey of Scotland, Lap worth, Swanston, and the 

 Authors. 



a. Thecse in bi-profile view, showing lacinia and septal strands. 



Enlargement of part of PI. XXXIV, fig. 5 a. 



b. Scalariform view, showing straight septal strand and scopulse. 



Enlargement of part of PI. XXXIV, fig. 5 c. 



Lasiograptus (Neurograptus) margaritatus (Lapworth). Plate XXXIV, figs. 6a — e. 



1876. Lasiograptus margaritatus, Lapworth, Cat. West. Scott. Foss., pi. ii, fig. 60. 



1877. Lasiograptus margaritatus, Lapworth, Proc. Belt". Nat. Field Club, p. 135, pi. vi, fig. 25. 



Polypary small and limp, about 1"5 cm. in length, with an average uniform 

 breadth of 1'5 mm. (exclusive of the lacinia). Thecae of the type of 



