346 GASTROPODA. [Pectinibranchia. 



Remarks. The axial sculpture is in the majority of the dredged 

 and more or less worn specimens almost completely lost. The species 

 is more slender than 0. impolita, the spiral cords more distinct and 

 mostly with wider interspaces, and the latter are, in well-preserved 

 examples, reticulated by axial threads. 



Fam. EULIMID,E, Adams. 



Animal with slender subulate tentacles and eyes sessile at their 

 outer bases; proboscis retractile, invaginate. when extended very 

 long ; mouth without jaw or radula ; foot elongated, produced in 

 front ; mantle with anterior rudimentary siphonal fold. 



Shell small, generally elongated, subulate or turriculated, shining, 

 polished, with spire usually curved or distorted ; aperture oval, pyri- 

 form, entire, with simple lip, the columellar margin more or less 

 thickened. Operculum corneous, paucispiral, sometimes absent. 



But little is known of the animals of these little shells ; it is probable 

 that the sexes are separated. They creep with the foot much in 

 advance of the head, which is usually concealed within the aperture 

 of the shell, the tentacles only protruding. They are more or less 

 parasitic on sea-urchins, holothurians, &c. 



Genus 1. EULIMA, Risso, 1826. 



Eulima, Risso, Hist. Nat. Eur. Merid., iv, 1826, 123. Type : E. degantissima, 

 Montag. Parithea, Lea, 1833 (in part). Balds, Leach, 1847. 



Animal having the body smooth, not ciliated, tentacles subulate, 

 approaching at the base ; eyes very large, nearly sessile, above and 

 slightly on the outside of their bases ; mantle not reflected outside, 

 and forming a siphonal fold ; foot lanceolate, grooved, truncated in 

 front, mention bilobed ; verge small, flattened, falciform ; opercular 

 lobe winged on each side ; branchial plume single. 



Shell not umbilicate, subulate, composed of many whorls, polished, 

 porcellanous ; commonly the spire is slightly twisted to one side ; 

 varices not well marked externally, but forming small ribs inside the 

 whorls, marking the position of successive mouths ; aperture ovate, 

 entire, angulate posteriorly and rounded in front ; columellar border 

 reflected. Operculum corneous, paucispiral, the nucleus near the 

 inner lip. 



The species inhabit tropical and temperate seas. 



The genus is known from all the Secondary strata, and became 

 abundant during the Tertiary period. 



KEY TO StIBOENERA. 



A. Shell subulate or subcylindrical, white, spire straight or curved EULIMA. 



B. Shell subulately turriculated, often with spiral coloured bands, 



varices on each side of spire more or less conspicuous . . LEIOSTEACA. 



C. Shell subulate, often coloured, with mucronate apex . . MUCKONALIA 



