414 THE GLAUCUS. 



The DENDEONOTUS derives its very appropriate name from two Greek words, the 

 former signifying a tree, and the latter the back. The beautiful branched gills are set in 

 a very shrub-like fashion upon the back, and even the tentacles and appendages of the 

 head are branched so as to correspond with the gills. In this and many other species 

 the digestive organs are covered with prolongations, which are carried into the little tuber- 

 culated appendages which stud the surface, and have given cause to M. de Quatrefages 

 to establish his theory of " phlebenterism," which he defines as " an anatomical arrange- 

 ment which is generally characterised by ramified prolongations of the digestive tube, in 

 virtue of which the digestive apparatus, to a certain extent, supplies the place of the 

 circulatory apparatus, and aids in the process of respiration." 



In his " Eambles of a Naturalist," Vol. I. note xv., the same author makes the 

 following valuable remarks : " At the same time I found in the Eolidinse a heart and 

 a tolerably well developed arterial system, but I could not distinguish any veins; 

 nevertheless, I was so imbued with the ideas of Cuvier, that it was long before I was 

 willing to admit the non-existence of these vessels. Nor was I convinced that there 

 were really no veins in the Eolidinse, until I had followed the same blood-corpuscule 

 throughout its entire circuit until I had seen it issue from the heart and pass through 

 the arteries by whose walls its movements were regulated, and until it was conveyed 

 through every pail of the general cavity and finally carried back to the heart." The 

 whole subject is too complicated and detailed to be here investigated, but it is of too 

 great importance to have been left without a brief notice. 



THE central figure at the bottom of the illustration represents the beautiful DOTO, 

 here shown in the act of making prey of a sea-anemone, which in vain withdraws its 

 tentacles and contracts itself into a shapeless mass at the touch of an enemy. It may be- 

 here remarked that the word Doto is the name of one of the sea nymphs of mythology, 

 and that in consequence of their exquisite colouring and beautiful forms, the names 

 of nearly all the nymphs have been given to different species of nudibranchs. The 

 tentacles of this animal are slender and can be retracted into certain trumpet-like sheaths, 

 which are seen projecting from the body. In this creature the processes of the digestive 

 system pass into the large appendages on the back ; and it is a curious fact that although 

 they fall off when the animal is handled, they are soon reproduced, and the creature 

 seems to suffer little inconvenience from their loss. Examples of this creature can 

 be found on the British coasts. 



THE remaining figures are representatives of another family, called the Eolidee. In 

 these creatures the theory of phlebenterism finds its best proofs, as the processes of the 

 digestive organs extend throughout the beautiful projections on the back, even though, as 

 in one genus, they are placed on footstalks. 



The beautiful EOLIS is common on our own coast, and may be seen moving over the 

 plants and stones with tolerable activity, and always keeping their tentacles and papilla 

 in motion, sometimes contracting and sometimes extending them, while the movement 

 of the water causes them to wave in a very graceful manner. These papilla possess the 

 property of discharging a milky kind of fluid when the animal is irritated. The fluid, 

 however, is quite harmless, at all events to the human skin. As in the previous case, the 

 papillae are liable to fall off at a touch. While using the dredge, the naturalist is sure to 

 bring plenty of nudibranchs to the surface ; but owing to their habit of contracting 

 themselves into a shapeless mass, an uninitiated observer will probably fail to notice them 

 and fling them overboard again, together with the seaweeds, stones, and other refuse 

 substances. The Eolis is a voracious being in spite of its delicate beauty, and if several 

 of them are kept in a vessel and not supplied with the sertularia and other zoophytes on 

 which they feed, they will attack and devour each other. 



OUE last and most remarkable example of the nudibranchs is the GLAUCUS, or 

 SEA LIZAED, the strange creature in the upper left-hand corner. In this animal the gills 

 are slender, cylindrical, and supported on three pairs of lobes or footstalks. 



