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 Mollusq. 1. 1. pp. 612, PI. i. figs. 917. 



Sp. Haliotis parva L., Hal. canaliculata LAM., GUERIN Iconogr., Moll. PI. 

 23, fig. i ; Haliotis Midce 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. AulobrancMata. Shell irregular, tubular, with 

 turns twisted spirally at the apex. Branchia3 pectinate. Sexes 

 separate. 



Siliquaria BRUG. 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 branchias placed at the fissure of mantle. 



Sp. Siliquaria anguina LAM., Serpula anguina ~L., BLAINV. Malacol., Prin- 

 cipes, PI. I. fig. ii. 



Magilus MONTPORT. 



Comp. E. KUEPPELL Memoirs sur le Magilus antiquus MONTF. ; Memoirca 

 de la Soc. d'Hist. not. de Strasbourg, Tom. i. Livr. 2, 1833, av. fig. Accord- 

 ing to RUEP. this animal belongs rather to the pectini branchiate molluscs 

 than to this family ; it lives in the Red Sea inclosed in cavities of Mean- 

 drince. 



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. BranchiaB arranged in a conical 

 series, at the left side of respiratory cavity. 



Sp. Vermetus lumbricalis, Serpula lumbricalis L., BLAINV. Malacol. PI. 

 xxxiv. fig. i, &c. 



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 



