392 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 16, 



exist in Aptychus. It cannot be a bivalve shell, but most likely be- 

 longs to Crustaceans, — the Phyllopoda. 



Loc. Duffkinnell, Dumfriesshire, in company with Graptolites. 



EXPLANATION OF PLATE XXL 

 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 b. 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. 2 b. 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. 



Graptolites. 



Fig. 3 a. Diplograpsus teretiusculus, Hisinger, sp. A cylindrical specimen from 

 Anglesea, Collection of Mus. Pract. Geol. Natural size. 



Fig. 3 b. ' . The same, magnified. 



Fig. 3 c. ■ . Lateral view, to show the cell-mouths. 



Magnified. 



Fig. 3 d. . A hollow mould in slate, from the same 



locality, much pressed in a longitudinal direction, so as to shorten all the 

 cells and press them into a zigzag form. 



Fig. 4 a. . A compressed specimen, from Dumfries- 



shire. Natural size. 



Fig. 4 b. . The same, magnified ; — the cell-mouths 



forming right-angled notches on the margin. 



Fig. 5 a. Graptolites Flemingii, sp. nov., from S. Kirkcudbrightshire. Nat. size. 



Fig. 5 b. . The same, magnified ; — the spines moderately 



decurved. 



Fig. 6. . A specimen much pressed laterally, so as to render 



the cells more oblique, and the spines more decurved. Magnified. 



Fig. 7 a. . A variety with less crowded cells, similarly, but 



more strongly compressed: the spines very much decurved. In this 

 specimen, as well as the last, the impression of the base of the cells is 

 marked by a transverse line. Natural size. 



Fig. 7 b. . The same, magnified. 



Fig. 8 a. Graptolites Sagittarius, Linn. A young specimen from Dumfriesshire. 

 Natural size. 



Fig. 8 b. . . The same, magnified : the cells occupy more than 



half the entire width. 



Fig. 8 c. . An older specimen, from the same locality. Na- 

 tural size. 



Fig. 8 d. — . The same, magnified : some of the cells bear spines 



on the lower edge of their mouths. 



Fig. 9 a. ? (G. laxus, Nicol). Magnified view of an ob- 



Hquely pressed specimen, showing the oval mouths and transverse im- 

 pressed line at the base of the cells. 



Fig. 9 b. . Scalariform impression of the same species, show- 

 ing the mouths and the oval openings from the base of the cells into the 

 common canal. 



Fig. 10. Bithyrocaris'i aptychoides, %'^.now. Natural size. The valves are quite 

 flat, and show the notch (*) at their upper angles. 



