APLYSIA. 555 



authors, since none exactly agree with ours, though there 

 can be scarcely a question that under the punctata of 

 Cuvier the British one is included. Since, however, there 

 is no doubt respecting its distinctness from the animal of 

 Bohadsch, which was the original depUans, a species which 

 we have ourselves examined in the Mediterranean, we are 

 obliged to fall back on the name h^'hrida, given by the 

 elder Sowerby to the Aplasia from Cornwall, figured by 

 him in the British Miscellany, but so badly, owing to the 

 condition of the specimen, that a person not acquainted 

 with the varying appearance of these curious creatures, 

 might fairly hold it to be a distinct species. None of the 

 figures in Rang's monograph of the Aplysia is sufficiently 

 like ours to warrant a reference, unless we should quote 

 the rosea of Rathke, which undoubtedly represents the 

 young of our species in its condition known as nexa. 



The shield is transparent, fragile, of a dark fulvous horn 

 colour, and of a somewhat elastic corneous texture ; the 

 surface is shining and nearly smooth, yet some obscure 

 radiating lines, or slight indentations, and some obscure 

 wrinkles of increase, are usually apparent. The upper 

 central dorsal area is convexly swollen, the slope from 

 thence downwards is gradual ; from thence to the sides 

 rather quicker. The general shape ranges from oval-acute 

 to oboval-acute, the lower and rather the longer portion 

 being semi-elliptical, whilst the upper end is obliquely sub- 

 rectangular, and the beak or apex, as it slants, bends a 

 little inwards, but does not exhibit the slightest vestige of 

 any spiral coil. Of the two edges which form the angle, 

 the shorter is somewhat incurved, and has but little decli- 

 nation ; the other is more convex, and almost forms a 

 continuous curve with the lower arch. The whole of the 

 internal area is manifest Occasionally the sides are less 



