ASTARTE. 313 



upper tertiary strata up to the Red Crag, the variety 

 elliptica being the more usual form in glacial deposits. 

 This form has not been found south of Great Britain ; 

 but the variety incrassata has a wide range in that 

 direction, throughout the Mediterranean and Helles- 

 pont to the Canaries. Northward this species reaches 

 Iceland, Upper Norway, and the White Sea, as well as 

 North America (and the variety elliptica as far as Spitz- 

 bergen), at depths varying from 3 to 160 fathoms. All 

 the other varieties which I have specified come from the 

 Hebrides and Shetland. 



The animal is very inactive ; and when buried in mud 

 the shell is often incrusted with a mineral coat like 

 tar. Specimens living in tenacious and fetid soil have 

 the beaks and umbonal area more or less eroded. They 

 are now and then distorted; and I found a large and 

 malformed pearl in one. The ribs are less numerous 

 and developed in southern examples of the typical form 

 than in those from more northern parts. The inside is 

 sometimes of a lovely salmoncolour. In specimens 

 from the Northumberland coast and Skye the front 

 margin is plain and the sides are crenulated. The 

 larger kinds of Asterias are said by M. Gay to prey upon 

 A. incrassata. 



I have failed to separate intermediate forms from 

 either the typical species or the variety elliptica. They 

 may belong to one or the other. Particular specimens, 

 and indeed the bulk of them, may be readily distin- 

 guished ; but although it may not be agreeable to the 

 mere collector, whose object is to get as many species 

 as he can, I must regard the Crassina elliptica of Brown 

 as only a variety and northern form of this most incon- 

 stant species. I have never in the course of my dredg- 

 ing- experience found them in company on the same 



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