OF MOLLUSCA. 3 



11. C. lividus, Fig. Moll. t. 12. f. 3. 



12. C. tseniatus, Fig. Moll. t. 12. f. 5. 



13. C. arenatus, Fig. Moll. t. 12. f. 8, 9. 



14. C. . Strombus, Fig. Moll. t. 11. f. 1, 2. 



15. C. raphanus, Fig. Moll. t. 11. f. 3. 



16. C? rusticus, Fig. Moll. t. 11. f. 4. 



17. C. sanguinolentus, Fig. Moll. t. 11. f. 5. 



18. C. (Cylinder) textilis, Fig. Moll. t. 10. f. 1. 



2. TlJLIPARIA. 



Veil of mouth fringed at the end. Teeth hastate. Operculum 

 ovate, horny. — Adams, Gen. Moll. t. 26. f. 2. 



1. T. Tulipa, Fig. Moll. t. 12. f. 2. 



2. T. striata, Fig. Moll. t. 10. f. 6. 



b. Aperture of shell wide. Operculum none. 



3. Rollus. 



Veil ? Operculum none. Shell subcylindrical, ventricose. 



Mouth large, wide. Spire short. 



1. R. geographicus. 



B. Mouth simple, not forming a produced rostrum-like veil over the 

 base of the proboscis. 



Fam. II. ACUSIDjE. 



Mouth exposed. Tentacles very small, close together on the side 

 of the mouth. Eyes none or very small, near or on the top of the 

 very small tentacles. Mantle enclosed, entire. Siphon elongate, 

 recurved. Teeth " elongate, swollen at the base, and furnished with 

 a denticulated keeled line as in Conus." Foot small. Shell turrited, 

 smooth ; spire very long. Mouth ovate ; inner lip rather concave ; 

 outer thin. Canal short, recurved. Operculum annular. 



The tentacles of Acusidce are exceedingly minute, placed on the 

 upper edge of the inflexed trunk ; in some species they are so small 

 as not to be seen ; some have the eyes on the tips of the small ten- 

 tacles, and others have no visible eyes. The male organ is very 

 filiform, very long, as long as two whorls of the shell. Foot small, 

 folded across when contracted. Head rounded. Mantle with a very 

 long, slender, breathing siphon. Operculum horny, ovate, nearly 

 as large as the mouth of the shell, with a rather thickened rib on 

 its inner side. The inner lip of the shell is generally absorbed and 

 concave ; in a few species only, as in Acus Cerithina, is it thickened 

 and elevated. 



The species of Acus live only below low-water mark. — Adams. 



The trunk of the genus Acus is represented as short and campa- 

 nulate by Quoy, t. 36. f. 17; but in other figures, as in fig. 19, the 

 muzzle is represented as produced. That the genus has a trunk, 

 and not a muzzle, is proved by fig. 31, where the anatomy is given. 

 In the same plate, Murex roseus, t. 36. f. 11, and M. ricinuloides, 



