GASTEROPODES. 273 
The main ducts terminate in the thickness of the side, at a consider- 
able distance from the head. 
A very great difference prevails both in the colour and in the general 
aspect of the specimens of this animal. Leaden grey, or a ferruginous 
hue, in general predominates ; and such, in as far as I have had an 
opportunity of observing, are always specimens of the largest size. One, 
extending about three inches, of transcendent beauty, was universally 
pure white, unless the central tuft of the corniculum, tending to the olive. 
It was taken near the Bass Rock. ‘Another, extending towards four 
inches, was of a beautiful transparent primrose-yellow. The branchize 
were very transparent ; the colour of all the rest uniform, rather more 
vivid than primrose-yellow ; and the aspect of the animal so beautiful 
and peculiar, that it seemed to me, at first sight, as if a new animal. 
Hombere’s Doris is rarely white ; but specimens an inch long occur 
sometimes several at the same time. No peculiarity is concomitant on 
the colour. The sole is always dingy white. Some adults are brown 
as copper, whereas smaller specimens are commonly grey, or almost 
white. 
Cuvier says he has assured himself of the presence of eyes. If so, 
they are probably deep seated, as he speaks from the result of dissection. 
Omission to specify the eyes of many of the minor animals, is not the 
denial of their existence, whether in the Doris or in others. The nature 
of the parts may oppose their detection. Colour may conceal them in 
one specimen, contrast may expose them in another. The powers of 
vision, in a different medium from air, cannot be satisfactorily estimated, 
without knowing much more of the organs. 
The whole body is susceptible of great alterations. The cornicula 
may be completely retracted ; and all its three portions are endowed with 
independent action. The branchix are susceptible of alternate con- 
traction and dilatation ; and the entire animal enlarges greatly, when 
crawling, above its dimensions in repose. In full vigour, and during 
genial weather, the specimen represented in Plate XX XVIII. figs. 1, 2, 
extended eight inches, whilst in motion. It seemed too heavy to attempt 
swimming supine, as done by smaller subjects. It is only under salubrious 
2M 
