156 P. W. GAMBLE, B.SO. 



Colour dark brov/n, with irregular yellowish spots ; the papillse each 

 with a dark band below a white tip. The general tint agreed closely 

 with that of the Fucus on which I found it after being dredged, and 

 upon which it rested in captivity. 



Oral veil with two prominent processes on each side, the outer ones 

 being the larger. Bhinophores retractile within calyx-like sheaths, 

 clavate, laminated at the base, with smooth truncate tips. Sheath- 

 margins produced into five papillse of very definite shape when fully 

 expanded. These papillse, like those of the oral veil and pleuropo- 

 dium, are capable of contraction and dilatation. Pleuropodium 

 consisting of four well-marked lobes on each side. The centre of each 

 lobe is dorsal and close to the middle line. It is marked by the large 

 dorsal papilla. The sides of the lobe extend anteriorly and posteriorly 

 in a ventral direction, enclosing an area concave outwards, and bearing 

 papillae. Posteriorly the lobes become slightly irregular and meet on 

 the dorsal surface. Foot slender, produced anteriorly into recurved 

 processes. Genital aperture beneath and slightly in front of the first 

 large dorsal papilla of the right side. Anus beneath the second. 



My attention was first drawn to the characteristic form and changes 

 of shape assumed by the dorsal papillse. These changes consisted of 

 contraction from an extended definite spiked shape to a more or less 

 bulbous triangular one. So far as I am aware none of the terms used by 

 previous authors on this subject do justice to the form of the extended 

 pleuropodial papilla. The interest of the matter is increased by the 

 fact that the tips of the "calyx-sheath" have the same power of 

 contractility, and that their extended form agrees with that of the 

 dorsal papillse. The velar processes also when extended are of a very 

 definite shape (see figs. 1 and 2). 



On gently touching the centre of the right side of the animal with 

 a clean sable brush three events occurred almost simultaneously ; the 

 rhinophores previously expanded were sharply retracted within their 

 sheaths ; the velar processes were extended ; and the dorsal papillse of 

 the right side, especially those near the point of the brush, were 

 erected from a previously oblique position, the large papillse markedly 

 directing their whitish tips towards the brush. The effect might be 

 almost said to be " bristling." The papillse of the left side were only 

 feebly affected. On repeating the experiment at different points I 



