234 THYONES. 



the suckers may be seen arranged regularly as in Cucum- 

 aria, while in the latter genus we occasionally find ex- 

 amples of a similar variation in the way of suckers, scat- 

 tered here and there between the avenues, thus indicating 

 an approach to Thjone. Some time after Oken had so 

 named these animals, Dr. Fleming, unaware of the cir- 

 cumstance, and equally perceiving the necessity of their 

 generic separation (which was indeed suggested by Cuvier), 

 constituted the genus under the name of Mulleria, which 

 name has been since applied by Jaeger to another section 

 of the tribe. 



The species before us was first observed by Muller, who 

 obtained it from the Faroe Islands. As a native of Bri- 

 tain it was first noted by Dr. Johnston, who published an 

 excellent description and figure of this species in the 

 seventh volume of the Magazine of Natural History. He 

 found it in Berwick Bay ; it is, however, by no means an 

 uncommon species on our shores. A few winters past 

 great numbers were thrown ashore after a violent storm at 

 Anstruther in Fifeshire, where they were observed by my 

 friend Mr. Goodsir. I dredged up a small one on the 

 Scallop-banks oif the Isle of Man in 1838; and it has 

 been taken on the Irish coast by Mr. W. Thompson, in 

 Belfast Bay and Strangford Loch. In Ireland it also 

 occurs on the west coast in Killery, and Mr. W. M'Oalla 

 pointed it out at Roundstone, Cunnemara, living in great 

 numbers buried in gravelly sand at low water, which cir- 

 cumstance accounts for the quantity of gravel usually 

 adhering to it. 



The Common Thyone measures from one to nearly three 

 inches, and is of a brownish-white colour, more or less 

 dusky, and of an ovate or pear-shape when at rest, though 

 it can lengthen itself considerably. When the tentacula 



