OF MOLLUSCA. 63 



1. A. perspectiva (Solarium p.), Quoy, t. 41. f. 5; Eydoux, t. 120. 

 f. 2; Adams, Gen. Moll. t. 25. f. 6. 



The foot of Architectoma perspectiva is very large, broad, folded 

 together on each side in the front half; the front edge truncated, 

 double-edged, rather produced, acute on each side of the front. 

 Tentacles two, conical, close together at the base, with a longitudinal 

 groove on the under side to the apex. Eyes on the upper part of 

 the outer side of their base. Proboscis very long, cylindrical, com- 

 pletely retractile. Teeth none ? 



2. TORINIA. 



Shell conical ; whorls square. Operculum circular, elevated, 

 conical, of many whorls. — Adams, Gen. Moll. t. 25. f. 7 a, b, c. 



1 . T. cylindrica. Solarium variegata, Quoy, t. 41. f. 3 ; Adams, 

 Gen. Moll. t. 25. f. 7. 



The tentacles of Torinia straminea conical, rather thick, 

 together at the base. Foot small ; angle of the front 

 edge rather produced, conical. Operculum thick, 

 horny, yellow, circular, as large as the mouth of the 

 shell, concave externally, annular, formed of several 

 concentric circles ; the inner smaller, most distinct ; 

 the outer edge thinner; inner side convex, with a 

 large central conical and more flexible thick yellow 

 process, half as long as the diameter of the operculum, with a rather 

 acute tip (fig. 34). 



3. BlFRONTTA. 



Shell discoidal ; whorls square, last produced, separate. Opercu- 

 lum like Torinia. — Adams, Gen. Moll. t. 25. f. 9 b. 



1. B. Zanclea (Omalaxis Z.), Adams, Gen. Moll. t. 25. f. 9 (shell 

 and operculum only). 



Fam. XXVI. TYLODINAD.E. 



Shell conical, depressed ; cavity very broad, simple. Animal like 

 Odostomia. Teeth ? 



1. Tylodina. 



1. T. punctata, t. 103. f. 7. 



2. T. citrina, t. 103. f. 1. 



Loven describes the body of Tylodina Duebenii as oblong, without 

 any rostrum. Chin deeply cut ; lobes lanceolate. Tentacles ear- 

 shaped. Gill dextral. Anus behind, subtubular. Foot strong, 

 thick ; sole ovate. Shell ovate, depressed, conical, obsoletely radi- 

 ated ; apex with two reversed sinistral whorls. Loven observes that 

 this genus has the same alliance to Odostomia as Emarginula to 

 Trochus. 



