98 WILD LIFE OF SCOTLAND 



rays, which may be described as flattened-out sharks. 

 These enclose the fertilised eggs in the parchment- 

 like or sea- weedy cases, picked up empty by children 

 on the beach, and popularly known as sailors', or 

 mermaids' purses. The curious long horns at the 

 corners are used to bind them to some submarine 

 object. 



In their passage down the oviduct, the ova receive 

 the case, much as the hen's egg receives its shell. 

 The female makes the first two horns fast by 

 moving round the mooring object, and then releases 

 the other two, and secures them at her leisure. A 

 slit on each side admits the free passage of water 

 through the case, and the inmates ultimately escape 

 by an opening at the square end. From the time 

 of deposition till the young pass into the sea, is 

 from seven to nine months. 



The smaller spotted dog-fish, or the dog-fish with 

 the smaller spots (Scyllium canicula), is not at all 

 common along the east coast. The larger spotted 

 dog-fish, a deeper water form, still less so. Both 

 increase towards Orkney and Shetland, and con- 

 tinue round the west coast to the English Channel. 

 , The North Sea, as will appear with regard to 

 other forms, is singularly free from pests of all 

 sorts. 



