BUTTHORN. 133 



above, sometimes a light pink or yellow, with purple 

 tips to the rays, furnishes no better characters. I have 

 now before me nine specimens taken at random from 

 various localities. They differ much in form, size and 

 colour. Four of them are from the east coast of Scotland ; 

 their marginal plates present all variations of spinosity, 

 and are severally on each side of the rays, thirty-two, 

 twenty-five, thirty-three, and thirty-four. The largest mea- 

 sures five inches across, that having twenty-five plates only 

 three. One is from the east coast of Scotland ; it measures 

 above five inches, and the rays have thirty-eight spineless 

 plates on each of their sides. One is from Shetland ; it 

 measures nearly three inches across, the number of plates on 

 each ray-margin is twenty-seven. Each plate bears one 

 spine. Two fresh specimens, a very little larger, present re- 

 spectively the numbers twenty-nine and twenty-three, and 

 the plates are spineless. A specimen from the Mediterranean 

 differs in no essential points from these. It measures three 

 and a half inches across ; the sides of each ray are bor- 

 dered by thirty plates, which bear two or three spines 

 each. Considering, therefore, these variations to arise 

 merely from age or situation, I see no ground for making 

 more than one species out of the Linnsean aurantiaca. 



Sometimes the whole of the upper surface is covered by 

 an adhesive glutinous matter, but this is by no means con- 

 stant. This variety is common in some parts of the Frith 

 of Forth. The species is very generally distributed. On 

 some of the southern shores of England it is common. Mr. 

 Harvey took it abundantly at Teignmouth. Dr. Johnston 

 takes it at Berwick-on-Tweed ; Mr. Bean at Scarborough. 

 It is generally distributed on the coasts of Scotland, and 

 occurs in both Orkney and Shetland. In Ayrshire it is 

 found by Mr. P. Maclagan. On the Manx coast it has 



