24 
THE YOYAGE OF H.M.S. CHALLENGER. 
by a sphincter, on the right side. On the other hand it opens into the pericardium 
as in all Mollusca. 
The heart (PL IV. fig. 1, n), within its large pericardium, lies at the base of the pallial 
cavity under the penis, above the kidney, and on the dorsal surface of the visceral mass. 
As was remarked above, gills are entirely wanting. Very probably in the Cym- 
buliidse, as in all the abranchiate Thecosomata {Clio, Cuvierina, &c.), respiration is 
carried on by some parts of the integument. 
The Generative Organs. — The genital gland (PL III. fig. 9, a) is slightly asymme- 
trical, its left side being more developed than the right ; it is somewhat excavated in 
front to receive the accessory glands and the genital duct. This latter (b), very thin at 
its origin, enlarges rapidly throughout its middle portion, and then narrows again till it 
reaches the accessory glands. It is not very long and surrounds these latter. 
They form a large mass situated anteriorly and a little to the right, and include a 
large muciparous gland ( d ) and a small albuminiparous gland (e) on the right side of the 
duct. These two glands, along with an ovoid receptaculum seminis (c) with a short 
duct, open into the distal enlarged portion of the genital duct. 
The genital aperture (f) is situated in front on the right of the visceral mass (Pl. IV. 
fig. 1, j). A spermatic groove, ciliated, proceeds from it towards the dorsal surface on 
the right side ; a little posterior to the genital opening, this groove becomes transformed 
into a canal by the fusion of its margins (Pl. IV. fig. 1 ). This canal opens into the 
cavity occupied by the copulatory organ. 
This latter, as I have already had occasion to remark, is situated on the dorsal 
surface of the head. It has the same structure as in other Thecosomata ; but the posi- 
tion of its orifice is different, being situated in the middle line of the dorsal surface of 
the head ( k ), a little behind the tentacles. 
The Nervous System. — The central nervous system (Pl. IV. fig. 1, o) is placed a little 
farther back than in the preceding forms. 
As regards the cerebral and pedal ganglia the central nervous system of Cymbulia 
resembles that of other Thecosomata (compare figs. 1 and 10, Pl. III.), asw~as recognised 
by van Beneden, Gegenbaur, and Souleyet. * That is to say — 
1. The cerebral ganglia are situated at the sides of the oesophagus (Pl. III. fig. 11, a), 
and united by a long supraoesophageal cerebral commissure (e). 
2. The pedal ganglia (b) are situated below the oesophagus, approximated to each 
other and to the cerebral ganglia ; they are not fused with the visceral ganglia, however, 
as is represented in the figure of von Jhering. 1 
These latter have been the subject of great disagreement among the four anatomists 
who have studied the genus Cymbulia, and especially between the figures and descrip- 
tion of one of them. 
1 Vergleichende Anatomiedes Nervensystemes und Phylogenie der Mollusken, pl. v. fig. 19. 
