REPORT ON THE NUDIBRAN CHIATA. 
Ill 
orifice projected the strong glans penis ; through the posterior orifice opens the duct of 
the mucous gland, and the aperture was partly filled by the bifid fold of the duct. The 
foot (figs. 14, 15, b) is strong and broad, projecting about 10 mm. from the sides of the 
body; the anterior end of the foot is truncate, rounded in outline; it has a fine marginal 
furrow ; the tail is short, about 1 '5 cm. long. 
The central nervous system is situated on the anterior part of the upper side of the 
bulbus pharyngeus ; it is depressed and small ; the length of the cerebro-pleural ganglia is 
about 7 mm. The cerebral ganglia (PL XIY. fig. 4, a, a) are broader anteriorly, and give 
off four nerves from the anterior border, one nerve running backwards from the external 
margin and two nerves from the upper surface, one of which is fine and delicate and the 
other stout and swollen into a ganglion at its base (ganglion opticum ?); no nerves appeared 
to take origin from the under surface. The pleural ganglia (fig. 4, b,b) are about equal 
in size to the cerebral ; each is divided by a deep fissure into a smaller inner and larger 
outer portion ; the latter alone gives rise to nerves — a thin delicate strand from the upper 
surface, and from the posterior margin four nerves, two of which are considerably 
stouter than the others ; from the under surface spring three delicate nerves (fig. 4). 
The pedal ganglia (fig. 4, c) are hardly smaller than the cerebro-pleural, and oval in shape; 
the cerebro-pedal and pleuro-pedal connectives are separated by a distinct cleft (fig. 4) ; 
from the internal margin of the ganglion two nerves proceed, of which one was considerably 
stouter than the other ; from the external margin four nerves arise, the anterior one being 
the stoutest ; the commissure uniting the two pedal ganglia (fig. 4, h) springs from the 
postero-external margin of each, and shows an indistinct division into two or three bundles. 
The cerebro-buccal connective (fig. 4, e,e) is rather long ; the buccal ganglia (PI. XIII. 
fig. 2 ; PL XIY. fig. 4 ,ff), situated upon the sides of the oesophagus, are large and oval, 
measuring about 4 - 25 mm. in length; each gives off four nerves, three posteriorly and one 
anteriorly ; the commissure uniting the two (fig. 4, g) was unusually long (about 2 ‘2 cm.), 
no trace of a gastro-oesophageal ganglion was detected. The nerve cells of the cerebral 
ganglia measured as much as '28 mm. 
I found no trace of eyes or otocysts. 1 The axial channel of the rhinophoria was 
wide and showing numerous variously sized apertures on the walls ; the nervus olfac- 
torius strong and somewhat swollen at the base of the club, forming a rudimentary 
olfactory ganglion (?) ; there were no spicules in the leaves of the club ; the two 
retractor muscles of the rhinophorion were very strongly developed. The skin proper 
of the back is easily separable from the next layer, and shows a number of perfora- 
tions, which correspond to the disks mentioned above, which are certainly merely 
1 Although after a careful examination I have not been able to detect eyes or otocysts, it is possible that both will 
be eventually found. On the “ abyssal theory of light ” there is no reason to doubt their presence. Eyes have been 
detected in a species of Pleurotoma dredged from a depth of 2090 fathoms, and in a Fusus from 1207 fathoms (Wyville 
Thomson, The Depths of the Sea, 1873, p. 465. K. Semper, Die natiirl. Existenzb. d. Thiere. Bd. i., 1880, pp. 103, 262 ; 
Animal Life, Internat. Sci. Series, p. 420, 1881). 
