168 THE GASTROPODA 
Posteriorly the mantle forms a large “ pallial lobe” under the pallial 
aperture (Figs. 98, 7.1; 148, I). The stomach is generally provided with 
chitinous, or even calcified, masticatory plates (Fig. 76, m.p). The visceral 
commissure is fairly long, except in such specialised forms as Runcina, 
Lobiger, and the Thecosomata (Fig. 60, m.s). The hermaphrodite genital 
aperture is connected with the penis by a ciliated groove, except in Actaeon 
(Fig. 148), Lobiger, and Cavolinia longirostris, in which the spermiduct is a 
closed tube. The Bullomorpha are swimmers or burrowers. 
Faminty 1. AcraronrpAk, Adams. Cephalic shield bifid posteriorly ; 
the margins of the foot slightly developed ; the genital ducts diaulic ; the 
visceral commissure streptoneurous ; the shell thick, with a prominent 
spire and elongated aperture; columella generally folded ; a corneous 
paucispiral operculum. Genera—Actacon, Montfort ; British (Fig. 148). 
Solidula, Fischer von Waldheim. Tornatellwa, Conrad ; extinct. Trzplaca, 
Tate ; from the Eocene. Adelactacon, Cossmann. Actaconina, d’Orbigny ; 
Carboniferous to recent. Bullina, Férussac. Bullinula, Beck. Actaeo- 
Fia. 147. 
Acera bullata, swimming, 
left-side view. f, fin (foot) ; 
m, mouth ; sh, shell. (After 
Guiart.) 
nella, VOrbigny ; from Fic. 148. 
the Cretaceous. Vol- Actacon tornatilis, removed from its shell, right-side view. 
altos 4 I, inferior lobe of the mantle; II, glandular hollow pallial 
varv, Lamarck ? Eocene. appendage (extending to the first whorls) ; III, pallial (hypo- 
Odostomiopsis, Thiele, branchial) gland; IV, opening of the pallial cavity ; V, eye and 
Tawny 2. Rincicv- cephalic hood ; VI, penis. 
LIDAE, Fischer. Cephalic disc enlarged anteriorly and forming an open tube 
posteriorly ; shell external, thick, with a prominent spire ; no operculum. 
Genera—Ringicula, Deshayes. Pugnus, Hedley. Cinulia, Gray ; from the 
Cretaceous. <Avellana, d’Orbieny ; from the Cretaceous. ortisia, Bayan ; 
from the Eocene. Famity 3. ToRNATINIDAE, Fischer. Margins of the 
foot not prominent ; no radula ; shell external with inconspicuous spire ; 
no operculum. Genera—Tornatina, Adams; British. Retusa, Brown, 
Volvula, Adams. Famtnty 4. ScAPHANDRIDAE, Fischer. Cephalic shield 
short, truncated posteriorly ; eyes deeply imbedded ; three calcareous 
stomachal plates, two broad and paired, one narrow and azygos ; shell 
external, with reduced spire. Genera—Scaphander, Montfort ; British. 
Sabatia, Bellardi ; Eocene. Atys, Montfort. Smaragdinella, Adams. 
Cylichna, Loven; British. Amphisphyra, Loven; British. Famriy 5. 
BuLuipak, d’Orbigny. Margins of the foot well developed ; eyes super- 
ficial ; three chitinous stomachal plates; shell external, with reduced 
