of Mollusca inhabiting these seas, which though not productive of pearly gems, or affording specimens for cabinet collections of Conchologists, or of amateur collectors, have attracted considerable attention in Europe, more especially since the publication of the splendid work of Alder and Handcock on the British Nudibranchiata.

The marine shells of Ceylon have long been known to the Naturalist, and they are also familiar to many in Ceylon, but the soft sea nymphs, or slugs, whose perishable charms often rival the more lasting beauties of the finest shell, had scarcely ever been noticed by any Naturalist or friend in the Island, till I had placed these creatures in the Vivarium. They have not only afforded amusement and instruction to myself, but, I hope, to others also, who have frequently seen these interesting creatures in their new homes. I must confess that some of my visitors were disappointed at the slimy nature of these animals, and failed to appreciate the beauty of many of my pet specimens. Others, however, more alive to the beautiful and to the wonderful works of God, did not despise the sea-born slugs, because they were so snail-like in appearance, and, like the land slugs, destitute of shells. Even the native shell divers, who procured me most of the living specimens, expressed their astonishment at the newly unfolded beauties of these "Addai," or slugs, which they found crawling on rocks and sca-weeds; but it was not till the full formed Doris, or the sweet little Eolis, expanded their tentacles and plumose gills in the glass Vivarium, that these men who go down to the deep' became aware, that the creatures which they so much despise are among the most elegant objects of the sea, and that, although a shell will preserve its colour for an almost indefinite period, the rich and variegated colours of these semi-gelatinous creatures, though shorter lived, are not less charming, or less worthy of admiration. It may, therefore, be hoped, that the interest recently created will continue to be attached to the naked Mollusca of Ceylon, and, that, in a few years, they will be as well known to

*T 'sea-slug.'

the Naturalist as the European species. Although it may be long before we shall find an Alder or a Handcock to pourtray gracefully, and faithfully record their characters and habits, still it will always be gratifying for me to feel, that I was the pioneer to the labours of others more competent to do justice to the Ceylon Nudibranchiata.

It has always been my endeavour, (though, I must own, often unsuccessfully,) to describe in familiar language to my friends in Ceylon, the Natural History of animals found in the Island, and therefore, if I have not attained this object in the following pages, it will not be from the want of a wish to impart to others some of the pleasure I have derived in such congenial pursuits or from the absence of a desire to be amusing as well as instructive.

Popular accounts of the Natural History of a country gener ally follow a scientific one. But I shall endeavour to combine. both in one communication, for I cannot but suppose that, among many inquirers, there will be found even a few who are anxious to dive deeper into the characters of an animal than its colour or form. Having this object in view, I cannot introduce the following descriptions of sea slugs, or sea nymphs, by a more intelligible and useful preface, than an abridged description of the Anatomy and Physiology of the Class Nudibranchiata, given in the English Cyclopædia; promising, in the course of my own descriptive account of the species found in Trincomalie, to detail faithfully their habits and characters.

NUDIBRANCHIATA.

A family of Gasteropodous Mollusca, characterised by the possession of distinct, external and uncovered gills. The species of the family are all marine, and with few exceptions small in size. They are sometimes, with other forms of animals, call d sca-slugs, arising from the fact that, like land slugs, they are destitute of shells. Their body is usually elongated and soft, and attached throughout its whole length to the foot, or disc, upon which they crawl. They are not unfrequently covered with a cloak, which in some is strengthened with calcareous spicula. The head is anterior, and frequently indistinct, having one or two pairs of tentacles, the upper pair of which are placed on the cloak when it is present,

and behind them the eyes are situated. But the characteristic peculiarity of these Molluscs is the appendages that constitute their breathing organs, placed upon the back, always symmetrically, in plumes, tufts or papillæ, either forming a circle on the central line, or arranged in rows upon the sides.

None of the Nudibranchiate Mollusca appear to have been known to the ancients, and even up to the time of Linnæus they remained, with one or two rare exceptions, entirely unnoticed. It was not until the appearance of the celebrated "Memoires" of Cuvier, in the Annales du Museum, that much attention was drawn to this subject. Since then, Lamarck and Blainville contributed something to the knowledge of their 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 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 globe. 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 the apparent deficiency of other genera, in comparison with the Dorididae, in foreign countries, arises from the want of proper examination, and from the little attention paid by collectors to the less conspicuous forms.*

*

*

In 1841, the celebrated Naturalist, M. Sars, announced the discovery, that these little creatures undergo a metamorphosis, having on their extrusion from the egg a very different form and character from those which they are afterwards destined to assume. In this first stage of their existence, they have the appearance of small animalcules, swimming freely through the water by means of two ciliated lobes, and have their body covered by a nautiloid shell furuished with an operculum. Up to

* Having paid this attention to "less conspicuous forms," I am enabled to add considerably in several genera.-E. F. K

that time nothing approaching to a distinct metamorphosis had been known to exist in any of the true Molluscs.

The Nudibranchiata exhibit a high state of organization. They are all provided with a powerful muscular buccal apparatus, which has, in some instances, appended to it a gizzard. The oral aperture is guarded by fleshy lips, and the mouth is furnished with a tongue, bearing a spiny prehensile membrane, and occasionally with lateral corneous jaws.

The œsophagus, stomach, and intestines are well marked; the former is generally short, and passes from the upper surface of the buccal mass. The stomach is frequently buried in the liver. The intestine is always short.

The liver presents two great types of form. In the Doridide and Tritonidæ it is entire (excepting in Scyllea, where it is broken up into 6 or 7 globular masses), occupying its normal abdominal position; in the Eolidide it is more or less diffused.

All the Nudibranchs are hermaphrodites, each individual being furnished with male, female, and androgynous parts. These organs, taken together, are very bulky, and occupy the greater portion of the abdominal cavity. They communicate with a common vestibule, opening upon a nipple-like process on the right side of the body, and always below the mantle, when it is present.

The organs of circulation and respiration consist of central organs of propulsion, a systematic and portal heart,-arteries, veins, and sinuses or lacunes; and of laminated, branched, or papillose branchiæ; arranged either on the medial line, or along the sides of the back. The flow of blood is rapid; the pulsations of the heart varying, in the different species, from 50 to 100 in the minute.

The nervous system presents a high degree of concentration, perhaps higher than in any other group of Mollusca,-and is divided into two very distinct portions:-one, the cephalic or excito-motor; the second, the splanchnic or sympathetic; these two portions intercommunicate at several points.

All the Nudibranchs are provided with auditory capsules. Eyes are also universally present. The dorsal tentacles are the organs of smell, and, judging from their great development, this sense must be more acute in most of the Nudibranchs than it is in any other Mollusc, with the exception perhaps of Nautilus. Touch undoubtedly resides everywhere in the skin, but it is specialised in the oral tentacles and parts about the mouth. The lips and channel of the mouth are probably the seat of taste,

Their ten city of life, when kept in confinement, varies much in the different species, but is greater than in many other marine animals.

Though patient and long-suffering in the endurance of hunger, they are very voracious. The greater number of them are carnivorous; living principally upon Zoophytes and Sponges. The Eolides do not scruple occasionally to devour the weaker among their own brethren.-Abridged from English Cyclopædia.

Hoping that the foregoing anatomical and physiological account of the Nudibranchiata, will draw more than ordinary attention to this family of marine creatures (found on almost every rock and sea weed), I shall proceed to give a descriptive account of upwards of a hundred species of marine-animals, including Sea-anemones and Planaria, found in the harbour, bays, and coves of Trincomalie. I cannot but regret, that not having with me Ruppel and Ehrenberg's work on species found in the Red Sea, I am not able to speak positively of all those herein described as being new to science. Some may, perhaps, have already been described by earlier observers, which, if ascertained to be the case, I shall only be too glad to take the earliest opportunity of acknowledging.

In concluding these prefatory remarks, I have to express my personal obligations to those authorities who have retained my military services in Ceylon, thereby enabling me to resume my Zoological labours, which were precipitately and unexpectedly shortened by my removal from the Island.

Trincomalie,

1st November, 1857.