212 NATURAL HISTORY. 



In Amphibola the shell is globular ; the columella fissured with a channel near the suture of the 

 outer lip ; the operculum is sub-spiral and horny. The animal is without tentacles ; the eyes are 

 placed 011 round lobes. It is an air-breather. Amphibola inhabits salt marshes near the sea, living 

 shells having SerpultK attached to them. They are found on the shores of New Zealand in great 

 abundance, living in pools of brackish water, and burying themselves alive at certain seasons in the 

 sandy mud. They are largely eaten by the New Zealaiiders. 



FAMILY XVII. LITORINIDJE. 



The mantle of animals of this family has a rudimentary siphonal fold ; the gills are uneqxiul, one 

 very large ; the head is muzzle-shaped, and the eyes are fixed at the outer bases of the tentacles ; 

 the foot is grooved along the under surface, and has a linear fold in front ; the tongue, which is long, 

 is furnished with seven rows of hooked teeth. The shell is spiral, top-shaped, or flattened ; aperture 

 simple in front, never pearly ; operculum horny, spiral, the whorls are few. 



Genus Litorina.* The Periwinkle has a compact, solid, turbinate (top-shaped) shell of few 

 whorls ; the spire is short, the aperture nearly circular, without any siphonal channel ; the outer 

 lip is simple and sharp-edged. The horny operculum fits it most exactly. The Litorina litorea 

 is collected in immense quantities around our shores, and is known by the familiar name of 

 " winkles," or " pin-patches." This species is oviparous^, and inhabits the lowest zone of seaweed 

 between tide marks. The Litorina rudis frequents a higher region, where it is scarcely visited by 

 the tide ; it is viviparous^ and the young have a hard shell before birth, in consequence of which 

 the species is not eaten. 



Both the Litorina and Trochus are the food of the Thrush in the Hebrides during winter. Peri- 

 winkles are largely employed by oyster growers to keep the beds and the "culch" clean by 

 eating up the slimy green weed that gi'ows so abundantly on oyster beds, especially in hot 

 weather. 



More than forty species of Periwinkles are found living on the sea-shore in all parts of the world. 

 When near the mouths of rivers (or as in the Baltic, which is less salt) they come in contact with 

 fresh water, and are liable to become distorted. 



In the caves of Southern France and Italy, along with mammoth and reindeer bones and ivory, 

 and in the sepulchral deposits at Aurignac, have been found shell necklaces or bracelets made of the 

 Litorina litorea, still abundant on the shores of the Atlantic, along with perforated shells of the 

 Miocene period, evidently gathered in a fossil state to be converted to purposes of personal decoration. 

 In the Megalithic tomb discovered in the year 1838 under the Knock-Maraidhe Cromlech, in the 

 Phoenix Park, Dublin, were found two male skeletons, underneath the skulls of which lay a number 

 of the common Litorina litorea, bored evidently for the purpose of being strung together as 

 neck ornaments. 



Genus Fossarus. This little shell is perforated, the spire is ribbed and striated, the inner lip 

 is thin, the operculum is not spiral. Its distribution is India, West Africa, and the Mediterranean. 



The genus Lacuna has a short spire, the shell is thin, the aperture is very large, the columella 

 is flattened and umbilicated ; it has a spiral operculum. The animal has lateral wings to its opercular 

 lobes and tentacular filaments. The species inhabit the northern shores of Norway, Britain, and 

 Spain, extending from iow water to fifty fathoms. 



Genus Litiopa.\\ This minute shell has a pointed spire, the aperture notched in front, the outer 

 lip thin ; it has a spiral operculum They are found floating on seaweed in the Atlantic and Mediter- 

 ranean ; they adhere by delicate threads. 



The genera Gheletropis and Macyillivrayia are also found gregarious in the open sea, and have 

 been referred to the Pteropoda by some, but Dr. S. P. Woodward refers them, in his later MS. notes, 

 to the Litorinidae. 



Genus Rissoa. This minute white shell (named after Risso, a French zoologist) is conical, pointed 



* From Latin, litus, litoris, the sea-shore. 



+ Oviparous, from ovum, an egg, a,ndpario, to bring forth. 



Viviparous, from virus, living, and pario, i.e., the young are born alive, as in Paludiiia. 



Any foreign body to which the young Oyster attaches itself when it ceases to be a free swimmer. 



I! Greek, litos, simple, and ope, aperture. 



