Gdtty Murine Lahoralori/ , St. Andreics. 3 



eacli side; the rim, then passing ventrally to the base of the 

 great flaps, is folded inward and upward, and is fused on 

 each side with the firm median mass over the mouth. In 

 the perfect condition with the branchiae attached, tlie pedicle 

 between the ventral flaps passes npward as a l)ifid process, 

 then expands into a lateral flap or wing on each side, which, 

 after a short progress, bends backward and upward, making 

 a kind of frilled knee, and becomes continuous with the 

 lining membrane of the branchiae of its side, its outer 

 border inferiorly pas^^ing into the basal semicircle of the 

 branchiae, to which it is fixed throughout. Such is the 

 arrangement connected with the floor of the mouth and 

 the lower lip. Dorsally the membrane forming the roof 

 of the mouth splits, considerably in front of the median 

 fissure of the lower lip, into two limbs, each of which at the 

 base has an axis with a narrow ventral web, and a thinner 

 and broader dorsal web wliich tapers distally and goes much 

 further along the axis than the former, the axis finally 

 tapering to a long delicate tip. The whole forms the so- 

 called tentacle which in the preparations is concealed in 

 each branchial semicircle. Viewed from the inner surface 

 of each branchial fan the "tentacle''^ has the web on its 

 dorsal edge connected with the dorsal edge of tlie fan, whilst 

 its ventral web passes ventrally to the central region dorsad 

 of the mouth. The inrush of water along the inner surface 

 of the branchial fan would thus be swept toward the mouth, 

 the tentacles and their webs probably aiding in this function, 

 and keeping the stream in each fan to its own side, as it 

 rushes down the groove by the outer border of the smaller 

 anterior web into the mouth. 



The branchial fan arises on each side from the firm base 

 formerly mentioned, a spiral twist being evident dorsally 

 and more especially ventrally at its commencement. Each 

 in preservation has the ventral edge curved inward, and a 

 narrow membranous web passes from the frill of the inferior 

 oral membrane for some distance along its edge. This 

 ventral border is the thickest, and gives origin to the 

 majority of the branchial stems, the rest springing from 

 the middle and posterior parts of the basal semicircle. 

 The number of these filaments varies, the two sides seldom 

 being identical — thus, for instance, 38 may occur on the 

 right and 41 on the left. The fan on each side is long and 

 graceful, banded with regular markings of dull red and 

 white. The circles of colour do not go evenly round the 

 expanded fan, but slant from the ventral fissure. Dorsally 

 a greenish hue occurs in some at the base of the fan. In 



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