NOTOMMATADvE. 40 



brain has a turbid yellowish appearance, at times clearly defined. The alimentary canal 

 is very large, darkly granulate, composed of many sacs ; and a slender rectum clearly 

 opens into a cloaca below the tubercular tail. Convoluted lateral canals run down each 

 side ; but no contractile vesicle could be discerned. 



The manners are sluggish ; it twists and wriggles much, with little change of place. 

 It is a fine large species, not devoid of elegance when extended ; but it often contracts 

 into very uncouth shapes. P.H.G.] 



Length, ^ inch. Habitat. Maidenhead; an aquarium at Torquay (P.H.G.) : rare. 



D. GIBBEK, Gosse, sp. nov. 

 (PI. XIX. fig. 7.) 



[SP. CH. Body encased in a transparent leathery sheath, hunch-backed; face 

 prone ; frontal proboscis small ; toes long, deciirved. 



In sediment from one of my window-reservoirs, I found this large Diylcna. About 

 the size of D. grandis, it much resembles that fine species in general appearance. Its 

 form is that of a cylinder, flattened along the belly ; the entire soft parts are encased in 

 what we might call a lorica, only that it is manifestly flexible : a difference, perhaps, 

 merely in degree. This sheath, of a glassy transparency, is almost unchangeable hi 

 shape ; yet it has marked creases here and there, which are permanent, serving for 

 needful flexibility. At what might be called the shoulders, it rises to a conspicuous 

 conical hump, diminishing thence by a gradual slope to the hinder parts. The internal 

 organs do not rise above the cylindrical body- wall, leaving thus an ample cavity within 

 the sheath all down the back ; quite empty, save that a very delicate conglobate gland, 

 attached by a thread to the hinder extremity, works up and down within it, by the con- 

 tractions and contortions of the animal. What seemed the trochal front was, through 

 the inclination of the head, nearly on the level of, and continuous with, the ventral sur- 

 face, and was covered with vibratile cilia. Behind, the body-sheath is cut off obliquely, 

 with a well-marked edge, for the emission of a stout foot, which carries two long curved 

 blade-like toes, often thrown widely apart. On each toe, at about one-fourth of its 

 length, there is an abrupt decrease of diameter on its superior edge, with the appearance 

 of a joint ; and a delicate line crosses each near its point. 



This individual appears to have been subjected to the remarkable accident of the 

 protrusion of the entire mastax, with all its accessories, from the frontal face, so that it 

 was totally unable to retract it. Whether this was the result of over-eagerness in feed- 

 ing, producing unguarded muscular exertion, or of violence from some of its predatory 

 foes, I cannot guess. I could discern no mark of any pinch on the body. But there 

 was a great extruded mass of flesh, amorphous and motionless, yet bearing a manifest 

 resemblance in outline to a mastax : while in an occasional glance that I could get at 

 its front, I saw what looked exceedingly like a long incus and a hooked malleus on each 

 side, though only the bottoms of these organs could be shaped, and that very vaguely. 

 Besides, there was not a trace of mastax to be seen within the head, for I searched 

 carefully for it ; the protruded mass was just where it would be, if such a misfortune 

 had occurred ; there was a conspicuous constriction behind the mass, evidently pre- 

 venting retraction ; while the mass was apparently of definite and unyielding shape, 

 containing hard and lengthened organs. The frontal disk, both above the mass and 

 also to a small extent below it, was covered with cilia in rapid, but feeble vibration ; 

 no whorls were produced in the surrounding floccose ; no swimming or crawling pro- 

 gress was made by the animal ; though it constantly contorted its body, and threw about 

 its toes. Its vital power was manifestly stricken, and even the movements gradually 

 grew feebler and feebler. I had not detected the slightest motion within the (supposed) 

 mastax ; its nerves had been probably paralysed at once. But fragments of the floccose 

 sediment kept on adhering to the exposed parts, as if these were glutinous ; and this 

 was more manifest at first than after some time. From the summit of the front a 

 minute finger-like proboscis descends. P.U.G.] 



VOL. II. E 



