﻿PLATE XIV. 



UPPER SILURIAN CRUSTACEA. 



Order — Merostomata . 

 Sub- Order — Eurypterlda. 



Fig. 



1 . Pterygotus bilobus, var. y, perornatus. 



1 a. Head, with the great maxillipeds or ectognaths still attached, but displaced outwards 

 on either side. 



The form of the head-shield, the compound facetted eyes (o, o), and the larval 

 eyes (le) are well seen. The joints of the ectognaths are lettered to cor- 

 respond with the names given to the articuli (see page 6, Part I). 



1 b. Facets of eye, magnified ten times. 



1 c. Facets of eye, magnified six times. 



(The form is evidently altered by compression.) 



1 d. Scale-like markings from the right coxal joint, magnified four times. 

 (The upper portion of the left coxal joint is restored.) 



2. A detached lip-plate, showing the lower edge (near the figure 2) to be truncated. (See 



also PI. XV, fig. 3.) 



3. Two beautifully preserved endognaths, found detached (the joints are lettered as in 



fig. 1). 



From the Uppermost Silurian of Lesmahago, Lanarkshire. 



Figs. 1 a, 2, and 3 are drawn, of the natural size, from specimens preserved in the 



Museum of Practical Geology, Jermyn Street. 



