304 PERIWINKLE confined to a few months or a year or more. The treatment therefore has no reference to re- covery, and consists in supporting the strength and relieving local symptoms. Occasionally the accumulation of fluid in the peritonea^ sac is sufficient to warrant its removal by tapping. PERIWINKLE, in zoology, a pectinibranchiate gasteropod shell, of the genus littorina (Fe>us- sac). The shell is univalve, with a few spiral whorls, the horny operculum made up also of a few spiral turns ; the tentacles are two, the two eyes being at the base on the outside ; the mouth is *t the end of a proboscis, the gills comb-shaped, and the foot moderate, with a groove on the lower surface. L. littoralis (Linn.), which abounds on the English and French coasts, is round, brown, longitudinally streaked with blackish ; the shell is thick, and without pearly lining ; it is oviparous, and lives in the lowest zone of seaweed between low and high water marks. L. littorea is pre- eminently the periwinkle of the British coast ; immense quantities are brought to the London market, and form a considerable article of food for the poorer classes ; after being boiled, the animal is picked out of the shell with a pin. Periwinkle. 1. Littorina littorea. 2. Littorina rudis. The rough periwinkle (L. rudis, Mat.), from the ocean washing the shores of Europe, fre- quents a higher zone of seaweed ; this is ovo- viviparous, and the young acquire a calcareous shell before they are excluded, for which rea- son the species is not eaten. There are many other species, all marine, inhabiting almost all parts of the globe, living on the rocks between the tide marks ; three species are very common on the coast of New England, of small size, and probably never eaten. PERIWINKLE (Lat. pervinca, probably from per, about, and vincire, to bind, from its use in forming chaplets ; old Eng. pervenke and per- vinke), a common name for species of vinca, which in this country are quite as frequently called myrtle and running myrtle. The genus vinca (Lat. mnculum, a band) belongs exclu- sively to the old world ; it is placed in the apo- cynacea, or dogbane family, which includes the oleander, allamanda, and other showy flowers ; some species have weak stems and are trailing, others are erect ; while most have evergreen leaves, there is a herbaceous one in cultivation ; the flowers have a somewhat bell-shaped tube, with a flat spreading limb having five broad oblique segments ; stamens five, inserted on the middle or upper part of the tube ; ovaries two, connected at the top by a single style, and becoming in fruit two elongated many-seeded pods, the seeds without the tuft frequently met Common Periwinkle (Vinca minor). with in the order. The best known species is the common or lesser periwinkle, V. minor, a native of Europe, and wild in England, though supposed to be introduced ; it is very common in gardens, where its weak stems spread upon the ground, taking root at the joints ; these long stems are sterile, the flowers being borne upon short erect stems, and solitary in the axils of their leaves, appearing in early spring, light blue, and in pleasing contrast to the smooth, dark green evergreen leaves. The large peri- winkle, V. major, is much larger in all its parts ; its leaves are also evergreen and shining, but Madagascar Periwinkle (Vinca rosea). have a fringe of minute hairs upon the mar- gins ; the erect flowering stems are a foot or more high, and the flowers quite large. This is not so common as the preceding, as it is less
