SEA-SCORPIONS 51 
that they are related to scorpions, and for this reason we call 
them Sea-scorpions. (See Plate IT.) 
The Crustacea are a very ancient race, as well as a flourishing 
one; some very old rocks containing undoubted fossils—namely, 
certain slates found in Wales and the Lake District—tell us of a 
Fia. 6.—Pterygotus anglicus, six feet long. 
1. Upper side. 2, Under side. (After H. Woodward.) 
time when shallow seas swarmed with little articulate animals 
known as trilobites. 
The best-known and largest of the Sea-scorpions is represented 
in Fig. 6. It has received the name Pterygotus (or wing-eared), 
from certain fanciful resemblances pointed out by the quarrymen. 
It was first discovered, along with others of its kind, by Hugh 
Miller, at Carmylie in Forfarshire, in a certain part of the Old 
Red Sandstone (see Table of Strata, Appendix I.) known as the 
