556 APLYSIADiE. 



arclietl, in which event the lower half of the shield has a 

 somewhat squarish aspect. 



A rather large specimen measured thirteen lines long, 

 and ten lines and a half broad. 



The general hue of the animal is a yellowish grey or 

 olive, minutely speckled with brown, variously spotted 

 with white, the spots often surrounded with darker rings, 

 and frequently compound, consisting of a central spot, sur- 

 rounded by a circle of smaller ones. The mantle lobes, 

 which are large and unequal, are pale at the edges, as are 

 also the tentacula. The latter have dusky tips. The sides 

 are often tinged with warm purplish brown. An un- 

 spotted variety occurs ; this is the mustelina of Davies and 

 depilans of many catalogues. The general shape varies 

 much according to the animal's position. When creeping 

 it is elongated, when at rest nearly globular. The back is 

 always very convex. The tentacles are cylindrical and 

 tapering, grooved beneath ; the eyes are small and black, 

 and placed at their anterior and lateral bases. The clear- 

 brown, very convex shield, is seen through the skin, but 

 its place is not marked by the radiating silvery lines de- 

 scribed by Philippi as occurring in punctata. 



A specimen which measured two inches long when at 

 rest, was double that length when creeping. When 

 alarmed it gives out a rich purple fluid, slightly odorous. 



Dr. Johnston notices an individual which had the lobes 

 bordered with bright blue. 



Young specimens are more elongated, and of a dark 

 purple colour. This animal occurs at intervals all round 

 our shores, and is very plentiful in many places both in the 

 north and south. It lives among sea- weeds and Zostera, 

 between low water-mark and five or six fathoms. We 

 have found it equally abundant at Guernsey and S. Devon 

 (S. H.); and Orkney (E. F.). 



