480 GLYCERA LAPIDUM. 



coat clasps two vessels at opposite poles, the contents of these being coagnlable and 

 staining deeply. The circular nmscnlar coat follows, and then the dense epithelial coat 

 intern all v. 



The proboscis in extrusion forms a long clavate organ, richly papillose, the individual 

 papilla being filiform (Plate LXXVI, fig. 1 a) with crenated edges. At the termination 

 of the first region are four blackish-brown teeth, each consisting of an elongated portion 

 hooked at the sharp tip, and also thinned off at the other end, where its muscles of 

 attachment are. On one side is a spur which becomes bifid after a short distance, and 

 to it other muscles are fixed. In the ordinary position in extrusion the four teeth are at 

 the angles of a square, and the long spur is vertical, the shorter passing inward obliquely 

 from each angle. The axis of the hooked tooth is nearly transverse. The aperture of 

 the proboscis is also transverse and in the centre. A symmetrical arrangement of the 

 muscular fibres further gives a character to the truncated terminal region at the 

 teeth. When the organ by a rupture of the body-wall is thrust out in its unrolled 

 position, the first region is marked by a series of longitudinal strise with the villi 

 internally. At the end is a ring of long processes like ruptured muscular fasciculi, 

 beyond which the four thick muscular masses for the teeth occur, followed by a somewhat 

 clavate part with ridges internally, and containing food. Such probably represents a 

 gizzard. A constriction separates this from the head-region, which at its commencement 

 has a series of strong muscular bands for retraction. 



So far as can be observed the first foot has three anterior lobes and a large rounded 

 posterior lobe. The dorsal is the most slender, the median next, and the ventral is much 

 broader, its outline being lanceolate. The posterior lobe is bluntly rounded. The dorsal 

 bristles are comparatively short and finely tapered. The ventral spread out like a fan 

 above and below the spine. The differences between the outer and central bristles of the 

 fan are slight. 



At the tenth foot (Plate LXXVI, fig. 1) the bristles are longer, but only one spine 

 occurs. The median lobe or papilla is longer. The change in the condition of the foot 

 occurs about the thirty-fifth, and is often recognized by the fact that the dorsal lobe, 

 instead of being folded backward, stands straight outward. The dorsal bristles are now 

 present (Plate LXXXV, fig. 3), but only a single spine, the second appearing about the 

 forty-fifth, though variation probably exists. The form remains similar at the fiftieth 

 foot, but the upper and lower compound bristles (Plate LXXXV, fig. 3 b) are thicker or 

 stronger than the median (Plate LXXXV, fig. 3 a), a feature still more marked at the 

 ninetieth foot (Plate LXXVI, fig. 1 b). The pointed condition of the three lobes is a 

 marked feature, and all are more or less anterior, though the ventral lobe is generally 

 sloped backward. The only posterior lobe is the bluntly rounded one behind the bristles. 

 A single spine supports the foot, the simple dorsal bristles passing from the spine toward 

 the dorsal papilla or lobe. At the base of the foot superiorly is the short papilla on the 

 side of the body. The differentiation of the ventral bristles into a diminishing series from 

 each edge is noteworthy. The foot appears to remain constant in its parts from the 

 anterior to the posterior end. 



Reproduction. — Specimens procured in Bressay Sound in July were laden with 

 nearly ripe ova. Dalyell's example spawned in July. 



