102 
THE VOYAGE OF H.M.S. CHALLENGER. 
sule, which showed a white dotted appearance under the lens, due to the presence of a 
number of somewhat round yellowish hard cells, occasionally there were a few long spicules 
not strongly hardened. The upper surface of the ganglia was coarsely granular in appear- 
ance. The cerebro-pleural ganglia were reniform, the two divisions of about equal size 
and hardly distinguishable from each other ; the pedal ganglia had a circular contour, and 
were about equal in size to the pleural. The large common commissure was hardly half 
as large as the diameter of the whole nervous system. The proximal olfactory ganglia 
(PI. III. fig. 2, a) were nearly sessile and bulb-shaped ; the distal form swellings about the 
same size upon the nerves (fig. 2, b). The buccal ganglia (fig. 1, a) were slightly smaller 
than the olfactory, egg-shaped, and united with each other directly ; the gastro- 
cesophageal (fig. 1, b,b), being about one-sixth the size of the buccal, attached by a short 
stalk to the side of the nerve. 
The eyes are attached by a short stalk to a hardly distinguishable ganglion ; their 
pigment is black and the lens yellow. The otocysts are a trifle smaller than the eyes, 
and contain a quantity of otoconia, about two or three hundred of the usual kind ; they 
are visible beneath the lens as chalk-white points. The broad, rather thin lamellae of 
the rhinophorial club, as might be seen by a lens, were covered upon their surfaces, but 
not on their margins by small pigment spots ; they contained numerous long rod-like 
pointed spicules, of a diameter of ’03 mm. scattered throughout. Through the stalk and 
on the walls of the cavity of the rhinophoria the tissue was filled with numerous quite 
similar spicules, sometimes rather stronger ; the retractors of the rhinophoria were as in 
other species. 1 The skin of the back was filled everywhere with spicules like those just 
mentioned ; the point-like knots on the back filled with spicules radiating outwards, and 
sometimes reaching the surface (PI. II. fig. 21). In the interstitial connective tissue were 
generally a number of round hard cells, 2 but only exceptionally spicules. 
The buccal tube had a yellowish-white colour, both inside and out; it was 6 ’5 mm. 
long by 5‘5 mm. broad behind; the three pairs of retractor muscles had quite the usual 
form. The strong bulbus pharyngeus was 7 mm. long by 6 '5 mm. in breadth and6‘7 mm. 
in height; the radula-sheath projected 3 ‘25 mm. behind; the strong retractor muscles 
as usual. The arched labial disk was covered with a strong white cuticle ; with a per- 
pendicular mouth-slit somewhat wider above. The tongue was strong ; the chitinous- 
yellow radula was provided with twenty-four series of teeth, within the radula-sheath and 
below the tectum indulge there were twenty-seven fully developed and three undeveloped 
series ; the total number being thus fifty-four. The first five or six rows were more or 
less incomplete ; in the seventh there were on either side ninety-one teeth, and the same 
number in the twenty-fourth row ; further back there was only an increase of at most 
two or three in the number of teeth to each series. The teeth were a clear yellow ; the 
height of the three outermost was about '09, ‘1, and T2 mm. respectively, and the 
1 Loc. cit., p. 511. 2 Loc. (At., Supplementheft i., 1880, p. 61, Taf. E. fig. 10. 
