﻿OF THE ORDER MEROSTOMATA. 33 



Order— MEROSTOMATA, Dana. 

 Sub-Order — Eurypterida, Huxley. 



Genus 1. — Pterygotus, Agassiz, 1844. 



Although Eurypterus was the first-discovered genus of this sub-order, both in this 

 country and also in America, as we have seen by the foregoing history, I have nevertheless 

 preferred to commence this Monograph with the genus Pteryyotus, as having become 

 historically the most important in England ; its affinities having been studied and its 

 structure described by such distinguished naturalists and palaeontologists as Messrs. 

 Agassiz, McCoy, Salter, Huxley, and Hall. 



The genus Pterygotus not only contains the largest species of the whole order, and 

 probably of the whole Crustacean class, but the remains of several of the species are 

 exceedingly perfect and complete. Even the great Pterygotus anglicus, which forms the 

 subject of this chapter, once only known by a few gigantic fragments, is now capable of 

 restoration from almost entire specimens figured in the accompanying plates. 



For the discovery and preservation of these very perfect remains we are indebted to 

 the accurate geological knowledge and untiring exertions of Mr. James Powrie, F.G.S., of 

 Reswallie, Forfar, who during many years has not only encouraged the quarry men to 

 preserve the organic remains from the " Arbroath paving-stone " and overlying shales, but 

 has also personally worked in the quarries of the district for days and weeks together to 

 procure specimens. 



No higher testimony can be afforded as to the value of my friend's labours than by 

 referring to the accompanying plates, the materials for which were nearly all furnished by 

 his own museum, those figured from the British Museum having likewise been procured 

 and presented by him. 



The great " Seraphim " of the Scotch quarrymen, Pterygotus anglicus of Agassiz, 1 was 

 the first species described 3 (1844), and is now very well represented, not only in detail, 

 by numerous detached organs and parts of bodies, but also by four nearly entire bodies of 

 various sizes. 



1 See Bibliography, p. 22, ^ 20. 



2 In Murcluson's ' Silurian System' (1839), p. 606, pi. iv, figs. 4 and 5, two fragments of Pterygotus 

 are figured and described by Prof. Agassiz under the name of Sphagodus pristodontus ; these have since been 

 referred by Mr. Salter (Mem. Geol. Survey, Mon. I, p. 89) to P. problematicus, Ag. 



