NUDIBRANCHIATE GASTEROPODA. 17 



the back, and projected only slightly from the hinder end of this; the rounded fore end was slightly 

 broader than the other part, with a marginal furrow; the foot-brim was narrow; the hinder end only 

 a little pointed (fig. 3). 



The central nervous system (fig. 4) was rather flattened, white, chiefly as in the Doridae. 

 The round cerebro-pleural ganglia (fig. 4 a) were a little larger than the likewise round pedal ones 

 (fig. 4b), the distinction between their two parts was not conspicuous; the chief commissures were 

 rather short; the globular buccal ganglia (fig. 4c) joined each other immediately. 



The eyes at the base of the rhiuophores had a diameter of o-io mm . The otocysts appeared 

 to contain a not great mass of pale otoconia, no spicules at all were seen in the dorsal skin, or its 

 papulae, nor in the leaves of the rhiuophores. 



The mouth-tube was short. The strong bulbus pharyugeus (figs. 5,6) reminded as to its 

 form somewhat of that in the Pleurophyllidiae. It was 3-25 mm long by a breadth of 3 mm and a height 

 of 275 mm . Its strongly convex fore side was covered by the large mandibles; from about the middle 

 of the somewhat convex hinder side the sesophagus originated; the radula-sheath did not project ex- 

 ternally. The fore side of the large and strong mandibles were (as in the Pleurophyllidiae) for the 

 greater part covered by a muscular plate which was, however, rather thin. The mandibles (fig. 7) 

 were amber coloured, only the masticatory edge was black brown; they were 2-5 mm long, and their 

 breadth taken together was 3-5 mm ; they were rather bent, so that their height reached almost 1-5"""; 

 along the middle of their length they showed a smooth, not deep excavation. The hinge-part was 

 rather short, as was also the masticatory process (fig 7a); the masticatory edge was not narrow; it 

 showed through its whole extent just to the hinge-part small roundish or angular facets (fig. 8) of a 

 diameter of o-oo55--o-oi ,nm . The tongue (figs. 9,10) was broad and flat, and projected only a little in 

 the buccal cavity; the little, forward and downward tapering radula was strongly and shining yellow. 

 The radula contained 15 rows of tooth-plates; further back, in the somewhat bent radula-sheath, 

 which was not to be seen from without, were 24 more rows, of which the three hindmost were not 

 yet cpiite consolidated; the total number of the rows of teeth were thus 39. The eight foremost rows 

 were very incomplete and the teeth worn; the foremost one contained only 6 and 7 toothplates 011 

 each side of the median one. The middle of the radula with the median tooth and two side-teeth were 

 sunk a little under the level of the side parts. On each side of the median one appeared up to 36 

 lateral tooth-plates. With the exception of the two innermost ones and the very outermost ones they 

 were of a strong yellow colour. The breadth of the clumsy median plates was o.o75 mm by a height 

 of o.io mm ; the height of the two outermost lateral ones was 0-035 — o-o4""»; then it rose quickly to o-io, 

 and continued thus towards the rhachis, the two innermost lateral teeth were much lower (pi. Ill, fig. 1). 

 The median tooth plates (pi. II, fig. 11 a; pi. Ill, figs. 1 a, 2 a) were short and clumsy, rather erect, 

 with a strong, broad base, hollowed in the fore edge, and with a short, strong, a little pointed hooked 

 part. The two first (inmost) lateral plates (fig. n b; figs. 1 b, 2 b) were of a deviating form with a quite 

 short and pointed hook. The other lateral plates (figs. 12; 1,2) reminded as to their form more of the 

 median plate, but the base was much smaller and the hook was longer. The 2—3 outermost lateral 

 plates (pi. Ill, fig. 3 a) were feebler, and the hook more pointed. 



The Ingolf-Expedition. II. 3. 3 



