The same, mutatis mutandis, may occur in sinistral shells.
Triforis, Physa, Clausilia are examples of sinistral Gastropods, but reversal also occurs as an individual variation among forms normally dextral.
When the shell issinistral the asymmetry of the organs is usually reversed, and there is a complete situs inversus viscerum, the direction of the spiral of the shell corresponding to the position of the organs of the body.
Finally, the original symmetry of the circumanal complex vanishes; the anus leaves the centre of the pallial cavity and passes towards the right side (left side in sinistral forms); the organs of this side become atrophied and disappear.
And Octa, after the death of his father Hengist, came from the sinistral part of the island to the kingdom of Kent, and from him have proceeded all the kings of that province, to the present period.
It was the age of the great literary and dramatic revival in England.
First and last, the woods remained his chief delight.
Gainsborough in his rural seclusion had been able neither by travel on the Continent to study the great masters of the past, nor to assimilate the traditions of the studio.
In connection with these observations I may mention the fact that in a certain pond in the North of England[19] the sinistral form of Limnaea peregra has been known to occur for about fifty years.
Occasionally the dextral circuit is followed in cases in which it is evidently less convenient than the sinistral would be, as in dealing cards in all ordinary games.
The Mokis also are careful to stir medicines according to the sinistral circuit.
On the outer surface this bowl has a row of tadpoles encircling it in a sinistral direction, or with the center of the bowl on the left.
This sequence is prescribed in Tusayan ceremonials, and has elsewhere been designated by me as the sinistral circuit, or a circuit with the center on the left hand.
Thus in a reversed or sinistral Flounder, which is normally dextral, the left side which is uppermost is still the left side, but it has colour and two eyes, whereas in the normal specimen the right side has these characters and not the left.
On this last hypothesis the mutation here considered might be a heterozygous specimen, with the dextral condition dominant in the head and the sinistral in the body.
The dorsal fin belonging to the normal sinistral body would therefore have a congenital tendency in the metamorphosis to unite with the head on the outer side of the original lower or right eye after it has moved to the left side.
This, with many similar beads, made of both dextral and sinistral shells, was associated with human remains in the great mound at Sevierville, Tenn.
The reverse whorl of the spire will be noticed, and the consequent sinistral character of the groove.
From the latter remark I should infer that some were made from dextral and others from sinistral shells; the two described are made from the Busycon perversum.
The sinistral valve of a bivalve shell may be known, by placing the shell, with its ligamentary or posterior part towards the observer; the sides of the shell will then correspond with his right and left side.
The sinistral circuit is one in which the center is on the left hand, while the dextral circuit has its center to the right.
