176 BRITISH GRAPTOLITES. 



received distinct names, although their peculiarities have long been recognised 

 and examples have been figured. 



Affinities. — D. ramosus may easily be distinguished from all other species of 

 Dicranograpti by its long biserial portion, which far exceeds in length that of any 

 other known species. The long uniserial stipes are also characteristic. 



Horizon and Localities. — Upper Glenkiln Shales and Lower Hartfell Shales. 



8. Scotland: Dobb's Linn; Hartfell; MoorySyke; Syart Law ; Mount Benger 

 Burn ; Railway cutting opposite Kirkton ; Gairy, head of Garryhorn Burn, etc. 

 N. Wales : Tiddyndicwm, Conway. 8. Wales : Prendergast Farm Lane. Ireland : 

 Ballygrot ; Craigavad ; Crawford's Burn (?) ; Ballymoney (?) ; Tramore Bridge, etc. 



Associates, etc. — I), ramosus is generally restricted to the Lower Hartfell Shales, 

 and is associated with Corynoides calicularis, etc. A few specimens have been 

 found in the Upper Glenkiln. In America, at the typical locality, it is associated 

 with characteristic Glenkiln species. 



The best specimens are those in the collections of the Geological Survey of 

 Scotland, the Natural History Museum, the Sedgwick Museum, and that of 

 Lapworth. 



Var. spinifer, Lapworth, MS. Plate XXIV, figs. 8 a—c. 



1870. Bicranograptus ramosus, Hopkinson, G-eol. Mag., vol. vii, p. 358, pi. xvi, fig. 5. 



1877. Bicranograptus ramosus, Lapworth, G-rapt. Co. Down, Proc. Belfast Nat. Field Club, p. 140, 



pi. vii, fig. 1. 

 1882. Dicranograptus spinifer, Lapworth, Grirvan Succession — Quart. Journ. Ceol. Soc, 1882. p. 610. 



Perhaps the most characteristic variety of 1). ramosus is that which Lapworth 



recognised in 1877 (he. cit., supra) as distinctive of the Glenkiln Beds, and for 



which he employed the MS. name of spinifer (loc. cit. 



ii2.- Dicranograptus ramo- supra \ This is characterised by (a) the fusiform shape 



s«,s. var spinifer, Lapw. J- ' j \ j r 



of the biserial portion, which is also considerably longer 

 than that of the typical form, and (b) by its strongly 

 spinose thecse. 



The biserial portion is 2 - 5 to 3 cm. in length and is 

 composed of some 30 thecse on each side. It has a 

 breadth of '5 mm. at the proximal extremity, but widens 

 rapidly to a maximum width of 2 mm. (exclusive of 



Biserial portion showing form of x , , ., •in c -j. l j_i i j_i ^ 



thecse and mesial spines, spmes) about the middle of its length, and then de- 



On same slab as PL XXIV, ^^ glightly towards fc } ie pomt f bifurcation. 



All the thecse of the biserial portion (with the possible 

 exception of some of the distal ones) are provided with long and stout mesial 

 spines. In consequence of the presence of these spines the outer walls of the 



