22 



edge of the afferent vessel is inserted on ihe upper end of 

 the mantle cartilage, near the insertion of the funnel 

 retractor; (6) the depressor muscle of the funnel, 

 runninc out from the funnel to the mantle, near the 

 branchial heart (fig. 8, F.D.); and (7) the great lateral 

 muscle running out from the eephalopedal mass to the 

 mantle (fig. 8, L.M.). 



The epithelium lining the mantle cavity is the 

 internal continuation, over the free border of the mantle, 

 of the outer skin of this structure, which here becomes 

 much thinner and loses its chromatophores, and hence is 

 transparent and colourless. However, the epithelium 

 covering the dorsal side of the visceral sac hears large 

 chromatophores, which show through the mantle during 

 life on account of the transparency of this structure. 



Stylets. -On removing the genital gland and the 

 posterior portion of the alimentary canal, the dorsal 

 portion of the mantle is exposed, internally. Two curved 

 tracks can he seen, roughly forming a Y-shape, posterior 

 to the depressors of the funnel (PI. Ill, fig. 13). By 

 dissecting away these muscles, and the great lateral 

 muscles, just at their bases, and then removing the inner 

 epithelium of the mantle, two colourless, semi-transparent 

 rods are exposed (PI. Ill, fig. 13, C.S.). These are 

 chitinous rods, oval in section and tapering at both ends, 

 which reach down almost to the posterior end of the 

 mantle, and are embedded in its substance (PI. Ill, 

 fig. 16, a and b). At the point of insertion of the funnel 

 depressor the rods are thickest. PI. III. fig. L5 3 

 represents a transverse section through Ihe stylet, in sitn 

 in the mantle. Each stylet is enclosed in and secreted by 

 the walls of an epithelial sac, on.e cell thick only. These 

 cells are columnar, and are rather longer at the two ends 

 of the sac than in the central region (fig. 15, Ep.S.). This 



