MOLLUSCA. 793 
In front, in the margin, an excision is seen in the direction of the 
holes, which afterwards, during the growth, becomes changed into 
a hole. The ventral disc or foot is adorned with a double row of 
feelers, tubercles, and fringes. The animal is attached to the shell 
by a large oval muscle. The branchial cavity opens by a fissure of 
the mantle on the right side, under the foremost holes of the shell. 
Comp. Cuvier Mollusg. 1.1. pp. 6—12, Pl. 1. figs. 9—17. 
Sp. Haliotis parva L., Hal. canaliculata Lam., GuéRIN Iconogr., Moll. Pl. 
23, fig. 1; Haliotis Mide L., Lister Conchyl. Tab. 613, fig. 5, &c. 
Many species of Haliotis bear a great resemblance to each other, and are 
difficult to distinguish. Some fossil specimens of this genus are met with 
in the tertiary formations. 
Family IX. Aulobranchiata. Shell irregular, tubular, with 
turns twisted spirally at the apex. Branchie pectinate. Sexes 
separate. 
Siliquaria Bruc. Shell thin, tubular, loosely spired; aperture 
rotundate, emarginate, with an incisure running with the spires to 
a short distance from the apex. Mantle cloven in the same part; 
pectinate branchie placed at the fissure of mantle. 
Sp. Siiquaria anguina Lam., Serpula anguina L., Buainv. Malacol., Prin- 
cipes, Pl. 1. fig. 11. 
Magilus MontFortT. 
Comp. E. Rurppenn Mémoire sur le Magilus antiquus Montr. ; Mémoires 
de la Soc. @Hist. nat. de Strasbourg, Tom. 1. Livr. 2, 1833, av. fig. Accord- 
ing to Ruep, this animal belongs rather to the pectinibranchiate molluscs 
than to this family; it lives in the Red Sea inclosed in cavities of Mean- 
drine. 
- 
Vermetus ADANSON. Shell thin, tubular, loosely spired, with 
spire adhering at the apex, elsewhere loose. Aperture orbicular, 
with margins connected. Head with two tentacles, oculiferous exter- 
nally at the base. Appendage of body replicate downwards, mostly 
furnished with an operculum. Branchiz arranged in a conical 
series, at the left side of respiratory cavity. 
Sp. Vermetus lwnbricalis, Serpula lumbricalis L., Buatny. Malacol. Pl. 
XXXIV. fig. 1, &e. 
Family X. Ctenobranchiata. Shell spirate or conical. Bran- 
chial cavity contained in the last turn of shell, open externally by 
a large fissure between body and margin of mantle, containing 
