80 



JOURNAL K. A. S, (OEYLON.) 



[Vol. III. 



and behind them the eyes are situated. But the characteristic pecu- 

 liarity of these Molluscs is the appendages that constitute their breathing 

 organs, placed upon the back, always symmetrically, in plumes, tufts 

 or papillae, either forming a circle on the central line, or arranged in rows I 

 upon the sides. 



None of the Nudibranchiate Mollusca appear to have been known to 

 the ancients, and even up to the time of Linnaeus they remained, with 

 one or two rare exceptions, entirely unnoticed. It was not until the 

 appearauce of the celebrated " Memoires" of Cuvier, in the Annates du 

 Museum, that much attention was drawn to this subject. Since then, 

 Lamarck and Blainville contributed something to the knowledge of, their I 

 physiology and relations, but not much to the number of species. 



Although little had been done up to this time by British Naturalists in 

 augmenting the species of this beautiful family, they have been, since, 

 the subjects of most accurate and fruitful research ; and the monograph 

 now publishing by the Ray Society, on the " British Nudibranchiate i 

 Mollusca," may be regarded as one of the most remarkable contributions 

 made to the literature of Natural History during the present century. 

 Continental naturalists have also added several new European species 

 during the last half century. 



With the imperfect knowledge of foreign species that we yet possess 

 it is scarcely possible to arrive at any satisfactory conclusion concerning 

 the general distribution of the Nudibranchiata in the different regions of 

 the glob©. The tropical forms are, as usual, larger and more brilliantly 

 coloured than those of colder climates, but the notices of extra European 

 species are so scanty, that we cannot form any idea of their numerical 

 preponderance. * * * * It cannot be doubted that a great deal of I 

 the apparent deficiency of other genera, in comparison with the Dorididce, 

 in foreign countries, arises from the want of proper examination, 

 and from the little attention paid by collectors to the less conspicuous h 

 forms.* 



M 



In 1841, the celebrated Naturalist, M. Sars, announced the discovery, j 

 that these little creatures undergo a metamorphosis, having on their j 

 extrusion from the egg a very different form and character from those b 

 which they are afterwards destined to assume. In this first stage of J 

 their existence, they have the appearance of small animalcules, swimming j 

 freely through the water by means of two ciliated lobes, and have their 

 body covered by a nautiloid shell furnished with an operculum. Up to 



* Having paid this attention to " less conspicuous forms," I am 'enabled to 

 add considerably to several genera. — E. F. K. 



