SEHA-SCORPIONS. 29 
forwards. We can fancy this creature propelling itself much in 
the same way as a “ water-beetle” rows itself through the water 
in a pond. In all other crustaceans the antenne are used for 
feeling about, but in the Pterygotus they are used as claws for 
seizing the prey. 
In general external appearance, this huge Pterygotus greatly 
reminds us of a tiny fresh-water crustacean, known as Cyclops— 
because it has only one eye, like the giant in Homer’s Odyssey. 
This little creature, which is only + inch in length, is an 
inhabitant of ponds. From its large eyes, powerful oar-like 
limbs, or appendages, and from the general form of its body, Dr. 
Henry Woodward (the author of a learned monograph on these 
creatures) concludes that the Pterygotus was a very active 
animal; and the reader will easily gather from its pair of 
antennz, converted at their extremities into nippers, and from 
the nature of its “jaw-feet,” that the creature was a hungry and 
predaceous monster, seizing everything eatable that came in its 
way. The whole family to which it belongs—including Pterygotus, 
Eurypterus, Slimonia, Stylonurus, and others—seems to have been 
fitted for rather rapid motion, if we may judge from the long 
tapering and well-articulated body. In two forms (Pterygotus and 
Slimonia) the tail-flap probably served both as a powerful pro- 
peller, and as a rudder for directing the creature’s course spat 
others, such as Eurypterus and Stylonurus, had long sword-like 
tails, which may have assisted them to burrow into the sand, in 
the same way that king-crabs do. Eurypterus remipes is shown 
in Fig. 2. 
It has been stated above that our sea-scorpions are related to 
the king-crabs. Now, this creature, it is well known, burrows into 
the mud and sand at the bottom of the sea. This it does by 
shoving its broad sharp-edged head-shield downwards, working 
rapidly at the same time with its hinder feet, or appendages, and 
by pushing with the long spike that forms a kind of tail. It will 
thus sink deeper and deeper until nothing can be seen of its 
