SEA-SCORPIONS. 33 
favour of such a change. It will thus be seen that our name 
Sea-scorpions is quite permissible. 
Hugh Miller described some curious little round bodies found 
with the remains of the Pterygotus, which it was thought were 
the eggs of these creatures ! 
Finally, these extinct crustaceans flourished in those ages of 
the world’s history known as the Silurian and the Old Red Sand- 
stone periods. As far as we know, they did not survive beyond 
the succeeding period, known as the Carboniferous.* 
1 The student should consult Dr. Henry Woodward’s valuable Monograph 
of the British Merostomata (Paleontographical Society), to which the writer is 
much indebted. With regard to the representation of Pterygotus anglicus in 
Plate I., it has been pointed out by Dr. Woodward that the creature was 
unable to bend its body into such a position as is shown there. As in a 
modern lobster, or shrimp, there were certain overlapping plates in the rings, 
or segments, of the body, which prevented movement from side to side, and 
only allowed of a vertical movement. 
