SEA-SCORPIONS 57 



in the sand by a process of wriggling backwards, as certain modern 

 crustaceans do, we may consider to be an open question. 



If only Sea-scorpions had not unfortunately died out, how 

 interesting it would be to watch them alive, and to see exactly 

 what use they would make of their long bodies, tail-flaps, and 

 tail-spikes ! Were they nocturnal in their habits, wandering 

 about by night, and taking their rest by day ? Such questions, 

 we fear, can never be answered. But their large eyes would have 

 been able to collect a great deal of light when the moon and stars 

 feebly illumined the shallower waters of the seas of Old Ked 

 Sandstone times ; and so there is nothing to contradict the 

 idea. 



Now, one of the many points of interest in Pterygotus and its 

 allies is that they somewhat resemble the crab in its young or 

 larval state. To a modern naturalist, this fact is important as 

 showing that crustacean forms of life have advanced since the 

 days of the sea-scorpions. 



Their resemblance to land-scorpions is so close that, if it were 

 not for the important fact that scorpions breathe air instead of 

 ivater, and for this purpose are provided with an air-tube (or 

 trachea) such as all insects have, they would certainly be removed 

 bodily out of the crustacean class, and put into that in which 

 scorpions and spiders are placed, viz. the Arachnida. But, in 

 spite of this important difference, there are some naturalists in 

 favour of such a change. It will thus be seen that our name 

 Sea-scorpions is quite permissible. Insects and Crustacea are 

 now included in the term Arthropoda. 



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 



