388 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 16, 



EXPLANATION OF THE FIGURES. 



Pl XXI Pterygotus problematicus. 



Fig. 1 a. Part of the claw of Pterygotus problematicus, Agass., from the Upper 

 Ludlow Rock of Hagley Park, Herefordshire : — this is probably the fixed 

 finger, and shows the striated spines of unequal size. 



Fig. 1 h. Some of the spines, magnified. 



Fig. 2 a. From the same slab : — a portion probably of the spinous edge of the ab- 

 domen, with one of the lateral appendages (*) attached. 



Fig. 1h. The appendage, fig. 2 a*, magnified, to show the radiating striae and 

 lateral teeth. This large spine or appendage may possibly be a terminal 

 joint of one of the feet, pressed against the fragment, fig. 2 a, but not 

 articulated with it. 



3. Description of some GRAPTOLiTEs/rom the South of Scotland. 

 By J. W. Salter, Esq., F.G.S. 



Mr. Harkness has been so good as to send me specimens of many 

 Graptolites he has collected, and information respecting several of 

 the localities mentioned in his paper, on the Silurian Rocks of the 

 South of Scotland, which appears in this Number of the Journal. 



He has added one very interesting species to the British list, by 

 finding the Diplograpsus teretiusculus, Hisinger, a species charac- 

 teristic of the alum slates of Sweden, at Glenkiln, Dumfriesshire. 

 He has also found D. ramosus. Hall, at Hartfell in the same district : 

 this previously was only known in Wigtonshire. 



Numerous specimens collected by him of the Rastrites triangu- 

 latusy Harkness, prove it, as Prof. M'Coy had surmised, to be ordy 

 the younger portion of Grapt. Sedgwickii, Portlock. A large series 

 too of 6r. incisus, Harkness, enables us to refer that species to 6r. Sa- 

 gittarius of Hisinger, of which there are good specimens in the 

 Society's Museum, and which has been lately well-figured by Geinitzf . 

 A figure of its young and full-grown stages are given, PI. XXI. fig. 8. 



Mr. Harkness also permits me to correct an error into which he 

 was led in his previous memoir J. The strata of South Kirkcudbright- 

 shire have been hitherto referred to the age of the Wenlock shale, 

 but the species of Graptolites quoted by Mr. Harkness from that 

 locality, would invalidate this reference ; viz. Graptolites (Diplo- 

 grapsus) foliaceus, Murch., G. tcenia, Salter, and G. ludensis, Murch. 



With regard to the first species, the evidence when examined turns 

 out to be quite inconclusive, and there is, as yet, no instance in 

 Britain of a double-graptolite being found above the Caradoc sand- 

 stone. 



G. taenia of his list proves to be an indeterminable fragment, and 

 the species itself, founded as it was on an imperfect specimen, must 

 be cancelled §. Geinitz has already referred it to G. Sagittarius. 



t Verstein. Grauwackenform. Sachs. Heft 1. Die Graptolithen, t. 2. figs. 2-7. 



% Quart. Journ. Geol. Soc. vol. vii. p. 55. 



§ The same must be said of Grapt. laxus, Nicol, described, but not figured, in 

 the Quart. Journ. Geol. Soc. vol. vi. p. 64. Most of the specimens are scalariform 

 impressions, and off'er very little to distinguish them from G. Sagittarius. 



