COMMON CROSSFISH. 85 



rays. The madreporiform tubercle is placed near the mar- 

 gin of the disk, between the origin of two of the rays. It 

 is large, convex, and finely striate, with waved radiating 

 stripe which bifurcate towards the margin. The colour of 

 this species is generally yellow or orange ; sometimes pur- 

 ple or red. It occasionally measures more than a foot 

 across, and generally from nine inches to a foot. In very 

 young specimens the pincer-shaped spinules are frequently 

 wanting. In that state it is the Asterias clathrata of 

 Pennant. 



The Common Crossfish varies considerably, sometimes 

 in colour, sometimes in the breadth of the rays, which, 

 when much attenuated, approach nearly in character to 

 those of the next species. There is a variety common in 

 the Frith of Forth, in which the spines of the dorsal ridge 

 are much developed and very prominent. Another variety 

 has the upper surface of a deep purple colour, the under 

 surface yellow, the arms much broader, and the skin more 

 leathery in texture than usual. It is 'a littoral form, and 

 for distinction may be called Uraster rubens, B. coriacea. 



This species abounds on most parts of our shores. It 

 may be regarded as the most common native Uraster. In 

 the Irish Sea it inhabits various depths of water, from 

 thirty fathoms to a few feet. At Liverpool it occurs under 

 stones at low water. In the Frith of Forth it is abundant 

 in from seven to ten fathoms. It ranges from Devonshire 

 to Zetland. Dr. Johnston takes it at Berwick-on-Tweed ; 

 Mr. Bean, at Scarborough ; Mr. P. Maclagan on the 

 Ayrshire coast ; and Mr. W. Thompson at Dublin and Bel- 

 fast. The coriaceous variety occurs abundantly under 

 stones at low water, and creeping on the sides of jetties 

 on many parts of the Fifeshire coast. Mr. Ball finds the 

 same form common at Youghal in Ireland, where it occurs 



