In a young blastoderm of Sepia viewed from the dorsal surface, a series of structures appear which are represented in fig. 111 A. In the middle is a somewhat rhomboid prominence which forms the rudiment of the mantle (_mt_). In its centre is a pit which forms the shell-gland. On each side of the mantle is a somewhat curved fold (_f_). These folds eventually coalesce to form the funnel. They are divided into two parts by a small body which forms the cartilage of the funnel. The smaller part of the fold behind this body gives rise to the true funnel, the part in front becomes (Kölliker) the strong muscle connecting the funnel with the neck-cartilage. In front and to the sides are two kidney-shaped bodies (_oc_), the optic pits. Behind the mantle are two buds (_br_), the rudiments of the gills. [FIG. 111. TWO SURFACE VIEWS OF THE GERMINAL DISC OF SEPIA. (After Kölliker.) _mt._ mantle; _oc._ eye; _f._ folds of funnel; _br._ branchiæ; _an._ posterior portion of alimentary tract; _m._ mouth. 1, 2, 3, 4, 5, arms; _p._ cephalic lobe.] In the somewhat later stage rudiments of the two posterior pairs of arms make their appearance outside and behind the rudiments of the funnel. The head is indicated by a pair of lateral swellings on each side, the outer of which carries the eyes. The whole embryo now becomes ciliated, though the ciliation does not cause the usual rotation. At a slightly later stage the second, third, and fourth pairs of arms make their appearance slightly in front of those already present. The posterior parts of the funnel rudiments approach each other, and the anterior meet the rudiments of the neck-cartilage. The gills begin to be covered by the mantle-edge, which now projects as a marked fold. At a slightly later period two fresh rudiments may be noted, viz. the oral (fig. 111 B, _m_) and anal invaginations, the latter of which is extremely shallow and appears at the apex of a small papilla which may be spoken of as the anal papilla. These invaginations appear at the two opposite poles (anterior and posterior) of the blastoderm. Shortly after this the rudiment of the first pair of arms arises considerably in front of the other rudiments, at the sides of the outer pair of cephalic swellings (fig. 111 B, 1).