158 : THE GASTROPODA 
Chenu. Shell spiral, conical, with flattened spire, umbilicated ; head 
short; tentacles split throughout their length; foot short. Genera— 
Solarium, Lamarck. Torinia, Gray. Fluxina, Dall. Faminy 52. 
ScaLARIIDAE, Broderip. Shell turriculated with numerous whorls and 
an elongated spire; head short, with a short proboscis; foot small, 
truncated anteriorly ; siphon rudimentary. Genera—sScalaria, Lamarck ; 
shell elongate with a circular aperture, whorls very convex, ornamented 
with longitudinal projecting lamellae ; British.  Eglisia, Gray. Crossea, 
Adams. Aclis, Loven. 
The three following families of Taenioglossa Platypoda have neither 
radula nor jaws, and are therefore called Aglossa. ‘They are suctorial 
animals with a well-developed proboscis, and are often commensal or 
parasitic on Echinoderms; some are abyssal. The series affords a 
remarkable example of the regressive evolution of various organs as a 
result of parasitism. Faminy 53. PyRAMIDELLIDAE, Gray, Summit of 
spire heterostrophic (Fig. 65, B); tentacles deeply grooved externally or 
split at their extremities; foot truncated anteriorly ; a projection, the 
“mentum,” between the head and foot; an operculum present. 
Fic. 137. 
Turbonilla scalaris, right-side view. f, foot; m, mouth; me, mentum; op, operculum ; pa, 
mantle; sh, shell; te, tentacle. (After Loven.) 
Genera—Pyramidella, Lamarck ; ‘columella folded, tentacles corniform. 
Turbonilla, Leach; columella not folded (Fig. 137). Odostomia, 
Fleming ; columella provided with a tooth; hermaphrodite ; British. 
Myxa, Hedley. Faminry 54. Evunimipar, Adams. Visceral mass. still 
coiled spirally ; shell thin and shining, generally with a pointed summit ; 
tentacles without a groove. Genera—Eulima, Risso; foot well 
developed, and with an operculum ; animal usually free, but some live 
in the digestiye canal of Holothuriae in the Fiji Islands, in the 
Philippines, and in Europe, e.g. Eulima distorta in Holothuria intestinalis. 
Niso, Risso. Scalenostoma, Deshayes. Hoplopteron, Fischer. Mucronalia, 
Adams (=Stylina, Fleming); foot reduced, but still operculate ; eyes 
present ; animal fixed by its very long proboscis, which is deeply buried 
in the tissues of an Echinoderm ; no pseudopallium.  Stylzfer, Broderip ; 
the operculum is lost, but a rudiment of the foot remains ; tentacles very 
small or absent ; eyes, otocysts, and a branchia present ; animal fixed by 
a large proboscis forming a pseudopallium which surrounds the whole 
of the shell except the more or less projecting extremity of the spire 
(Fig. 20); sexes separate; parasitic on all groups of Echinoderms in 
different seas. | Hntosiphon, Koehler and Vaney ; visceral mass still 
coiled ; shell much reduced; proboscis very long, forming a pseudo- 
