138 MESSRS. ALDER AND HANCOCK ON 



large, rounded organ, with the interior laminated. This is apparently the same as the 

 pancreatic origin in the Dorides. 



The central portion or tube of the gastro-hepatic apparatus is large and folliculated : 

 it opens into the left side of the stomach, a little in advance of the belt of horny pro- 

 cesses. From this point, and from the corresponding point on the opposite side, folli- 

 culated branches are sent to the anterior branchial processes ; and similar branches 

 from the central tube penetrate the posterior processes. The hepatic glands within the 

 processes are very slender, and are delicately branched. All these characters of the 

 digestive system are alike common to Tethys, with the exception of the belt of horny 

 processes encircling the stomach, and the branching of the hepatic gland within the 

 branchial processes, which two features seem to distinguish Melibe. 



The reproductive organs also closely resemble those of Tethys -. there is the same 

 peculiar form of the mucous gland in connexion with the female channel, the same 

 single, almost sessile, spermatheca, and the same rounded compact gland interposed 

 between the glandular tube of the penis and the oviduct. 



In the nervous system this relationship is likewise seen. The principal ganglions are, 

 as in Tethys, fused into a single mass ; and, as in that genus, they exhibit in the same 

 conspicuous manner the globular structure well known in the Mollusca, the whole 

 mass being composed of distinct globules of various sizes. The eyes are sessile on the 

 anterior portion of the cerebral mass. 



Melibe fimbriata, n. sp. (PI. XXXIII. figs. 6, 7.) 



Body elongated and elevated, nearly linear, much compressed at the sides, and taper- 

 ing to a narrow tail ; skin rather thick, soft, and covered throughout with slender fim- 

 briated filaments ; colour ochre-yellow, deepening to fulvous on the back, spotted and 

 blotched with darker shades of the same colour. Veil large, convex, covering Ihe head 

 like a hood ; the margins fringed with numerous linear filaments. Tentacles with nine 

 or ten laminae, sharply angulated at the sides, and divided in front by a strong midrib ; 

 they are placed within cup-like sheaths, supported on long, narrow, linear footstalks, 

 situated on the posterior part of the veil. Branchial processes very large, wedge-shaped, 

 thin, and coming to an edge at the upper margin, which is widened a little and trun- 

 cated ; much thickened below, where they are attached by a slight peduncle : the sur- 

 face is fimbriated like the body. They are set in a row of six or seven on each side of 

 the back, extending nearly to the tail, the posterior ones smallest ; they are flexible, and 

 often bent over at the ends. Foot very narrow and grooved. Length 7 or 8 inches. 



The Melibcea viridis of Kelaart is probably a variety of this extraordinary-looking 

 animal in a young state ; but as the name of viridis is quite inappropriate to our species, 

 and would lead to an erroneous impression of its colour, we have not thought it desirable 

 to adopt it, especially as this name has not got a footing in science. A small, white. 



