NOTAEOLIDIA. 21 



irregular intervals. In all there are about ninety on each side. They are 

 somewhat wrinkled, and this rugose appearance is increased by their bearing 

 a little white pigment, arranged in irregular lines. In front the side-flaps 

 turn inwards, so that the cerata stand in front of the rhinophores ; but they 

 are set distinctly on the flap, and not on the head. Behind, the cerata of the 

 two sides meet at the tip of the tail, the free portion of which is very small and 

 hardly 1 rnm. long. The dorsal margin and cerata are irregularly undulated. 



There is no frontal veil, but the region in front of the rhinophores passes 

 directly into two very thick, conical, oral tentacles, 6'5 mm. long, and 5 broad at 

 the base. Between them lies the mouth, which seems small and circular, but is 

 much contracted. The anterior margin of the foot is grooved, and perhaps notched ; 

 but this character could not be ascertained with certainty, owing to contraction. 

 The foot is folded inwards, but in a natural condition must have had wide, expanded 

 margins, and have been about 10 mm. broad. The rhinophores, which are set close 

 together, are about 4'5 mm. high, and bear fifteen distinct perfoliations. At the 

 base are folds of skin, but not regular pits. The genital orifices are 13 mm., and 



PIG. 22. Notaeolidia depressa RHACHIDIAN FIG. 23. Notaeolidia depressa RHACHIDIAN TOOTH 



TOOTH FROM ABOVE. FBOM THE SIDE. 



the vent 20 mm. from the head. The former are small, and not surrounded by 

 large folds of skin ; the latter is an elongate papilla, half way down the side. 

 The pericardium is not prominent. 



The internal organs are poorly preserved, but appear to resemble those of 

 N. gigas in their essential features. The central nervous system is small, the eyes 

 black and minute. No salivary glands were discovered, but they probably exist. 

 The jaws are thin, with a smooth edge. The formula of the radula is 20 x 4.1.4, 

 and the teeth are much as in N. gigas, but the central tooth (figs. 22 and 23) is not 

 so square, and has sloping sides. It has a rather lower median cusp with eight to nine 

 strong denticles, but is not striated. The laterals are higher and narrower, with deeper 

 and more distinct denticulations. Even the outermost lateral has about twelve fine 

 but clear denticulations. The cesophagus is short, the stomach large, strongly 

 laminated, and constricted in the middle. The liver is folliculate, and arranged much 

 as in N. gigas. The main trunk gives off six branches on each side, which form a 

 layer of ramifications in the mantle margin and sides of the dorsal area, from which 

 diverticula pass into the cerata. The space filled by this layer is considerably 



