REPORT OX THE PTEROPODA. 
53 
the right side, a little further forward than in the Pneumonodermatidge, are certain very 
delicate organs (which I was not able completely to isolate in the badly preserved speci- 
mens examined) which I regard as the heart and kidney. 
The Generative Organs. — These resemble those of all the other Gymnosomata, the 
genital gland and duct being disposed in the same fashion. The hard body situated on 
the right of the visceral mass, whose relations Souleyet was not able to make out, is 
nothing else than the muciparous-gland, which, as in some other Mollusca, becomes 
strongly hardened by alcohol. The receptaculum seminis is like that of other genera. 
The genital aperture, as may be demonstrated by transverse sections, is situated in 
the usual position, behind the base of the right fin, and not as represented by Souleyet, 1 
who probably mistook the opening of the penis for it. This latter opens at the base of 
the right lateral lobe of the foot, and for the rest does not differ from that of other 
Gymnosomata. 
The Nervous System of Halopsyclie is very difficult to study by dissection. The 
ganglia are so exceedingly small (the length of the whole animal being scarcely more 
than 4 mm.), that they are crushed by the points of the finest needles, and can only be 
properly distinguished by the aid of compound lenses of short focus. 
Further, of the three zoologists who have treated of the organisation of Halopsyclie , 2 
two have not mentioned the nervous system. Souleyet is the only one who has described 
and figured it, and even he does so inaccurately, his representation being defective — 
1. In the number of commissures (he shows only the pedal commissure) ; 
2. In the number of gangfia (he records eight, whilst in reality there are only seven). 
The arrangement of this nervous system, like the rest of the organisation, supports 
the view that the genus Halopsyclie belongs to the Gymnosomata, for it is constructed 
on a plan very different from that of the Thecosomata, whilst it agrees in its general 
disposition with that of the Gymnosomata. 
The cerebral ganglia, instead of being placed at the sides of the oesophagus and 
connected by a long supraoesophageal commissure, as in the Thecosomata (PI. I. fig. 7 ; 
PL II. fig. 10 ; PI. III. fig. 11), are approximated to each other and situated above the 
oesophagus (PI. V. figs. 9, 10, 11, a). 
Each of them gives origin to two principal nerves : — 
1. A lateral nerve (PI. V. fig. 10,/), soon swelling into an elongated ganglion, which 
occupies the nuchal tentacle. The optic and olfactory nerves of the preceding Gymno- 
somata are not then to be distinguished in the present instance, a fact which is due to 
the atrophy of the eye. 
1 Voyage de la Bonite, Zoologie, Mollnsques, pi. xv. fig. 3, o'. 
2 Huxley (On the Morphology of the Cephalous Mollusca, Phil. Trans., 1853, p. 40); Macdonald (On the Anatomy 
of Eurybia gaudichaudi, Trans. Linn. Soc. Lond., vol. xxii. p. 245); Souleyet (Voyage de la Bonite, Zoologie, t. ii. 
p. 250). Von Jhering (Vergleichende Anatoinie des Nervensysternes und Phylogenie der Mollusken, p. 242) only 
republishes, in a few lines, the data of Souleyet, including the inaccuracies. 
