NUDIBRANCHIATE GASTEROPODA. 



The form of the animal is almost spherical (fig. i, 2), a little flattened on the lower side (the 

 foot), strongly reminding of a gigantic Ochidiopsis. Below the region of the rhinophoria a little for- 

 ward and a little behind is found a trace of a dorsal brim (fig. i), otherwise the back bends smoothly 

 and without anv distinct margin downwards and inwards towards the foot, so that the body has no 

 sides properly speaking; anteriorly the body passes without any distinct border into the head (fig. i). 

 To each side of the back of the neck the short-stalked club of the rhinophore (fig. i) was seen 

 projecting from its hole the edge of which was smooth; the club contained about 80 rather narrow 

 leaves. The fore-end of the head was large, roundish, rather flat (fig. 1) with vertical-oval aperture, 

 in which the light bluish-white labial disk appeared; from the sides of the head the strong, some- 

 what compressed, tapering (fig. 1) tentacle projected freely; the narrow chin below the head was 

 smooth (fig. 1). - - The evenly and strongly convex back (fig. 1, 2) was everywhere covered with 

 small, disk-like depressed or slightly elevated figures of a diameter of 0-5 — 2 mm , the centra of which 

 were either further depressed or rose to a cone of a height of at most i mm ; the depression would seem 

 to have been caused by a strong retraction or a rubbing off of the little cone. Towards the fore end 

 of the back was seen on each side the projecting margin of the round holes of the rhinophoria, and 

 farther forward the but little conspicuous smooth dorsal edge behind the back of the neck (fig. 2). 

 On the hinder part of the back are seen the rather large, flat branchial tufts (fig. 1), placed in a 

 large circle, which is completed in the median line behind by the short and powerful anal papilla. 

 The number of the branchial tufts were 10; on the left side the three hindmost were drawn closer 

 together, and above these was one more isolated; on the right side three and three were closer 

 together. Each tuft showed a short, black-coloured stalk, from which 3—5 tri- and quadripennate 

 leaves spread flatly. The anal papilla was a little depressed, truncate, with a slightly crenate aper- 

 ture directed backward and downward (fig. 1). The rather large space circumscribed by the branchial 

 circle, showed a number of smaller and larger small diks like those on the other parts of the back; 

 forward and a little to the right, close to the hindmost branchial tuft of the foremost right group, 

 was seen the renal pore (fig. 1) a little projecting. — The sides of the body are quite low. 

 Anteriorly, on the right side, behind the region of the rhinophore, the outer genitals were seen, 

 foremost the opening of the prreputium with a little projecting fold, and behind it the adjoining vulva 

 with its two colossal, indented sidelobes (fig. 2). -- The foot is powerful, broad; the fore margin with 

 a deep transversal furrow (fig. 2), the side margins not very conspicuous, the tail rather short (fig. 1). 

 The intestines were nowhere to be seen from without; the coverings of the back were thin, 

 mostly only o'3 mm thick; the thickness of the foot in the middle about 3"™. The intestines were by 

 short, cobweblike connective tissue attached to the foot and the sides of the back as well as to each other. 

 The broad and flat central nervous system resting on the hinder part of the bulbus 

 pharyngeus, was of a slightly yellowish white colour; its breadth was i6 m,n by a length of the cere- 

 bral ganglia of up to 5"5' nm and a thickness of up to r$ mm . It was wrapped in a very thin, but ad- 

 hering capsule, which was prolonged out on the larger nerves. The cerebral ganglia (pi. II, 

 fig. 2aa) are the largest, and anteriorly considerably broader 1 ), the commissure between them short 



r ) On the before examined specimen (comp. 1. c. p.m. pi. XIV, fig. 4) the hindmost part of the supraoesophagal 

 ganglion was thin, and was li\ me wrongly interpreted as belonging to the pleural ganglion. 



The Ingolf-Expedition. II. 3. 2 



