Lapworth— Graptolites of Co. Down. 
138 
which are usually referred by palaeontologists to this species, all agree in the 
possession of a tapering polypary, destitute of proximal ornamentation; perpen- 
dicular, short, square, hydrothecae; and straight, or very gently undulating 
suture. 
^ Var. a. tectus . Barrande. (Grapt. de Boheme. *P| 1, figs. 
19 and 20.) 
Virgula never distally prolonged. Locality— Rare in the Gala Group of 
South Scotland, unknown as yet in County Down, 
go. Var. b. normalis. Lapw. PI. 6, fig* 3 1 • 
Polypary with sub-parallel margins. Virgula greatly prolonged distally. 
Locality— Abundant in Coalpit Bay. 
Var. c. Climacograptus rectangularis. M‘Coy. PI. 6, fig. 32. 
Virgula prolonged, proximally only, to a considerable length. Polypary 
tapering. Locality— Unknown in Ireland. Rare in the Birkhill Shales of 
Moffat. 
g 2< Var. d. Climacograptus caudatus. Lapw. PI. 6, fig. 34. 
Polypary tapering, several inches in length, with stout virgula prolonged 
both proximally and distally to a length equal to that of the polypary itself. 
Locality — Unknown in Ireland. 
Var. e. Climacograptus tubuliferus. Lapw. PI. 6, fig. 33. 
Polypary with parallel margins, virgula distally prolonged and expanded 
into a long flattened plate or vesicle. Locality— Camalea. 
In Scotland each of the foregoing forms has a definite range in the 
succession of Silurian deposits. They are all most certainly very intimately 
allied, but it is possible that we may eventually be forced to look upon them 
as distinct species. Such of these forms as are known upon the Continent have 
a corresponding vertical range, and appear to possess similar external 
features. 
64. Sp. 2. Climacograptus Scharenbergi. Lapw. PI. 6, fig. 36. (Catl. 
West. Scott. Fossils. Plate 2, fig. 36). 
Polypary diprionidian, about an inch in length and one-twelfth of an inch 
in average diameter; proximal end ornamented with a short radicle 
