17 



7. laevigata, Linn. 10. praetenuis, Couth. 12. tuberculosa, Adams. 



8. perspicua, id. 11. Sitkensis, Adams. 13. zonata, Gould. 



9. plicatilis, Milll. 



Figure. 



Velutina laevigata. PL 22. Fig. 124. Shell, showing its light, in- 

 flated, coriaceous structure. 



Family 3. CAPULACEA. 



Shell ; conoid or cap-shaped, sometimes resting on a shelly plate, 

 and mostly furnished with an internal shelly appendage. 



Two very natural groups of Limpets are associated in this family, con- 

 nected, nevertheless, by a character in the animal of secreting from the 

 foot a shelly basal plate in its place of attachment. The first comprehends 

 two genera, Pileopsis and Hipponyx, whose shells have more the form of a 

 cap. They have no internal appendage, and are mostly parasites upon 

 other shells. The second group, which comprehends the interesting series 

 of Cup-and-Saucer and Slipper Limpets, known as the Calyptraidae, have 

 all an internal shelly appendage, varying from a slender half-funnel, and 

 largely developed cup, to a laterally compressed fold, and spirally cham- 

 bered trochiform septum, or a cross deck. The genera are — 



Pileopsis. Calyptilea. Trochita. 



Hipponyx. Crucibulum. Crepidula.. 



Genus 1. PILEOPSIS, Lamarck. 



Animal ; ivith a head produced into a, proboscidiform muzzle ; 



tentacles two, long, subulate, unconnected, with the eyes or 



bulgings at their external bases ; mantle fringed at the margin; 



branchial plume single ; foot strong, suborbicular, its sides 



plain. 

 Shell ; cap-shaped , obliquely conical, covered with a soft velvety 



epidermis, with the vertex incurved ; aperture largely dilated. 



The well-known Hungarian Cap Limpet, which is an inhabitant of our 

 shores, and ranges throughout the European seas from Norway to the 

 Mediterranean, represents a genus numbering many foreign species which 



VOL. II. D 



