186 SPATANGACE^E. 



upper surface is rough, with little eminences For the smaller 

 spines : but between the ambulacra there are many larger 

 eminences, surrounded by a depressed ring ; these are for 

 the larger spines, and similar eminences abound on the 

 under surface. The anus is transversely oblong, and sur- 

 rounded by an oval ring. Below the anus, and placed in 

 a great measure beloAV the body, is the post-anal impres- 

 sion, large, and broadly reniform. The mouth, which is 

 transverse and narrow, is surrounded by a star of five 

 lanceolate ambulacra. 



In England this species is said to be rare. Pennant 

 records it from Weymouth. On the Scottish coast Dr. 

 Fleming states it is common in the Frith of Forth. In 

 Ireland Mr. W. Thompson informs me it is rare, and is 

 found on the coast of Wicklow. On the Scallop-banks off 

 the Isle of Man it is abundant, and is generally found on 

 the cleanest part of the bank, among the Scallops. On its 

 spines we sometimes find in considerable numbers, a little 

 parasitic bivalve Mollusc, the Montacuta substriata. 



In foreign countries it is found on the Norwegian coast, 

 on the shores of France, and in the Mediterranean Sea. 



In the vignette I have represented the Pedicellarise of 

 Spatangus purpureas. 



