236 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



rous system. Apparently, it did not commence to exist so soon as its 

 gigantic ally, the Pterygotus ; but it continued to live on longer, and 

 attained its maximum of size in beds higher than those in which 

 Pterygotus is known to have been found. 



EXPLANATION OF PLATE X. 



Kg. 1. Eurypterus Symondsii, Salter. Head. Upper beds of the Cornstones, 

 Old Red Sandstone, Kowlestone, Brecknockshire. 

 „ 2. E. ^oovle^'f mbbert ^^g-\^ ^^^, of Old Red Sandstone, 



ment oi a body-rmsr. \ -tr-n. ^ ■\r■^^ 



„ ^a,^b. Edgeofthecarapace.} Kiltorkan, Kilkenny. 



„ 4. E. pygmseus, Salter. Head, body-joints, and swimming-foot. Downton 



Sandstone, Kington. Mr. R. Banks's collection. 

 „ 5. Head, body-joints, and ] Basement-beds of the Old 



tail. i Red Sandstone, Ludlow 



,, 6. Tail. J Railway. 



7. Part of the head, magni- 

 fied, showing ornament. 



8. Part of first body -joint, 



magnified. 



9. E. megalops, Salter. Head, 



magnified. 

 10. Head, natural size. 



Upper Ludlow Rock, Ludford. 





; 



Base of the Old Red Sandstone, 

 Ludlow Railway. 



11. The eye and a portion of the margin of the head. Base of the 



Old Red Sandstone, Ludlow Railway. Mus. Pract. Geology. 



12. —Part of the head, mag-^ ^^^^ ^^ ^^^ ^^^ ^^^ Sandstone, Lud- 



low Railway. Mr. R. Lightbody's 

 collection. 



nified, showing the granular 

 surface. 



13. Body-joints and tail. 



14. Tail. Base of the Old Red Sandstone, Ludlow Railway. Mus. Pract. 



Geology. 



15. E. Hnearis, Salter. Tail-joint. Upper Ludlow-rock, Ludford ; Kington. 



Mus. Pract. Geology. 

 16 a, 16 h. — Tail. Downton Sandstone, Kington. Mr. R. Banks's col- 

 lection. 



17. E. acuminatus, Salter. Tail. Passage-beds at the base of the Old 



Red Sandstone, Ludlow Railway. Mr. Lightbody's collection. 



18. E. abbreviatus, Salter. Tail. Downton Sandstone, Kington. Mr. R. 



Banks's collection. 



19. E. acuminatus ? Body -joints and tail. 



20. Eurypterus ? Chelate termination of antenna ? Bone-bed, Ludlow. 



Mr. Lightbody's collection. 



