PURPLE-TIPPED EGG-URCHIN. 1 63 



on a smooth space, and separated from the next by a 

 finely granulated space. 



The Purple-tipped Egg-Urchin is abundant in the Irish 

 Sea, as also on the west coast of Scotland. The Rev. 

 Gilbert Laing has sent me a specimen from Orkney. Mr. 

 Thompson takes it in the north of Ireland, and Mr. Ball 

 at Dublin and Youghal, where be informs me it is " usually 

 dredged up adhering to the dead valves of oysters and other 

 bivalves. In England it has been observed on the southern 

 shores, and I have found it in Guernsey. In the month of 

 August 1839, when seeking for marine animals at low 

 water on the coast of the last-mentioned island, I had 

 the pleasure of seeing one of these Urchins exclude its eggs 

 spontaneously through the ovarian holes. 



The Pedicellarise which abound on the spines and near 

 the mouth of this Egg-Urchin form very interesting micro- 

 scopic objects. They consist of a head of a rounded form, 

 apparently bearing three bill-like blades, mounted on a long- 

 flexible pedicle, which is itself placed at one end of a long 

 stalk with a bell-shaped extremity at each end made of 

 the same substance with the head. When highly mag- 

 nified, the stalk and head appear to consist of a fleshy 

 substance, having regular transverse rows of granules im- 

 bedded ; an appearance represented by Sars in his drawings 

 of the Pedicellarise of Echinus sphara. A toothed line 

 borders the granular space of the bladed part, and a simi- 

 lar toothed line, marking the junction of the blades, runs 

 down the centre. All these appearances are well seen in 

 specimens preserved in spirits, and are represented in the 

 vignette at page 174. 



M '£ 



