REPORT ON THE PTEROPODA. 
81 
3. Gizzard or Stomach. — Almost all the Bulloidea have a stomach armed with homy 
plates, usually three in number, almost symmetrical (one dorsal, and a lateral one on 
either side). This number is, however, variable, as is also the symmetry of the plates. 
Thus in Scaphander the three plates are irregular, the dorsal being very narrow. In 
Acera there are nine such plates, and in Runcina [ = Pelta ) four symmetrically disposed 
as in the Theocosomata, 1 so that in this respect the Bulloidea differ much more among 
themselves than Runcina differs from the Thecosomata. 
Besides this there are in many Bulloidea in front of the three large symmetrical plates 
twice as many smaller plates, just as in the Thecosomata [Bulla hydatis , 2 Bulla striata , 3 
Haminea cornea , 4 &c.). 
4. Liver. — Philine and Bulla are said to have two hepatic ducts ; 5 the less 
specialised Cavolinise ( Cavolinia trispinosa 6 and Cavolinia quadridentata, Pl. III. 
fig. 4, h, j) have also two. 
5. Anal Gland. — The gland which is found in the Cavoliniidse ( Clio, Cavolinia) to 
the left of the visceral cavity at the extremity of the rectum, almost symmetrically 
with respect to the osphradium, exists also in the Bulloidea ; I have seen it in Bulla 
striata, Haminea hydatis (PI. II. fig. 3, h), and Haminea cornea; in Scaphander it 
occupies a prolongation of the mantle which accompanies the visceral sac for several 
turns of the spire (as Vayssiere 7 has already observed) ; in Actseon the arrangement is 
similar to that of Scaphander, but the extension formed by the gland is much longer and 
reaches as far as the first coils of the spire. 
The Generative Organs. — In Philine 8 and Doridium 9 there is a vesicula seminalis 
comparable to that of certain species of Cavolinia (e.g., Cavolinia tridentata). 
The Nervous System. — The cerebral ganglia are separated from each other and con- 
nected by a long supraoesophageal commissure, both in the Bulloidea and the Theco- 
somata. The pleural ganglia are fused with the cerebral in the Thecosomata to form a 
single mass which is usually undivided externally. This is also the case in Actaeon 
(PI. II. fig. 11) ; in all the other Bulloidea the pleural ganglia are situated near to the 
cerebral ganglia, so that the cerebro-pleural connectives are either very short or not 
discernible. We have further seen that in the Thecosomata, e.g., in Cymhulia (PI. IV. 
fig. 2), the stomato-gastric nervous system has the same arrangement as in the Bulloidea 
[Philine) : an anterior and a posterior ring connected by threads passing between the 
horny stomacal plates. 
1 Vayssiere, Recherches anatomiques sur les genres Pelta et Tylodina, Ann. d. Sci. Nat. (Zool.), ser. 6, t. xv. 
pl. i. fig. 4. 2 Vayssiere, Recherches anatomiques sur la famille des Bullides, loc. cit., pl. xii. fig. 111. 
3 Vayssiere, Recherches zoologiques et anatomiques sur les Mollusques Opistobranches du Golfe de Marseille, 
i. Tectibranches, loc. cit., pl. i. fig. 4. 1 Ibid., pl. i. fig. 11. 
6 Vayssiere, Recherches anatomiques sur la famille des Bullides, loc. cit., p. 88. 
6 Souleyet, Voyage de la Bonite, Zoologie, t. ii. pl. ix. fig. 30. 
7 Vayssiere, Recherches anatomiques sur la famille des Bullides, loc. cit., p. 90. 
8 Ibid., pl. x. fig. 83. 
(zool. CHALL. EXP. — PART LXVI. — 1888.) 
9 Ibid., pl. viii. fig. 68. 
Uuull 
