466 Mr. C. Collingwood on Nudihranchiate Mollusca. 



the largest specimen I have seen being also the darkest. In the 

 aquarium this species exists longer than any other mentioned in 

 the present paper, and remains attached to corallines for weeks 

 and even months, moving about but little, and freely depositing 

 its minute ribands of spawn. 



Eolis papulosa. — We have at least eight species of Eolis 

 proper, of which this is the largest and one of the least beautiful. 

 It is found pretty generally distributed upon the shores of the 

 Mei'sey ; but being usually of a sooty colour, it is not I'eadily 

 distinguishable without special search. At the present time the 

 spawn of this species is pretty abundant on the Cheshire shore, 

 in the form of long convoluted cords upon the sides of stones ; 

 but the animal itself is comparatively seldom seen. I have 

 never tried to keep this species in the aquarium, for its anti- 

 actinial propensities are too well known ; but in a small separate 

 vessel of water it remains almost motionless, and dies in two or 

 three days, perhaps for want of food. F.olis papillosa is a veiy 

 protean species, and has been known under many synonyms. 

 In the 'Annals of Nat. Hist.' (vol. ix. p. 34), an Eolis is described 

 by Messrs. Alder and Hancock, under the specific name of 

 obtusalis, which sometimes occurs upon the Egremont shore. 

 This differs from the ordinary form of E. papillosa in being less 

 than one-third the size and of a much lighter colour. But 

 more extended observation led the ingenious authors to discard 

 it as a species, and to consider it as a variety of Eolis papillosa. 



Eolis coronata. — Of all the species of the genus Eolis, I know 

 of none which combines elegance of form with delicacy of colour- 

 ing in a more eminent degree than this ; and it is the most 

 common Eolis found in the Mersey. It may be taken in nearly 

 all the localities, and all the year round, adhering to the under 

 side of stones. It is a very active species, constantly moving 

 about or swimming, with its foot uppermost, on the surface of 

 the water, by a graceful but mysterious method of propulsion. 

 It most resembles Eolis Drummondi in external appearance, but 

 may be at once discriminated from it by the delicate dash of 

 ultramarine which exists in the papillae. In the aquarium it 

 lives for some weeks, freely depositing its little convoluted 

 circlets of spawn. Mr. Byerley informs me that, a few years 

 since, some specimens found on the Egremont shore were sent 

 to Mr. Alder, who pronounced them to be the darkest-coloured 

 examples which had come under his notice. In the Mersey it 

 seldom exceeds an inch in length. 



Eolis Drummondi. — Next to the last, if not as common, is 

 this species, which vies with it in elegance of form, though 

 hardly perhaps in richness of colouring. It is met with in 

 nearly all the localities, and at all seasons. The specimens found 



