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 



1 The student should consult Dr. Henry Woodward's valuable Monograph 

 of the British Merostomata (Palseontographical 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. 



