74 STEENSTRUPIA FLAVEOLA. 



one-sidedness of the simple tentacle arrested the motions of this Steenstrupia, I fancied that- 

 the animals before me had by accident been deprived of their corresponding marginal 

 appendages. But among hundreds of specimens secured in the bays of both sides of Zetland, 

 there was never the slightest sign of a symmetrical arrangement by the development of more 

 tentacles than one. 



Plate XIII, fig. 1, a, represents Steenstrupia rubra of the natural size ; l,h, magnified, 

 as seen in profile ; 1, c, the arrangement of tentacular bulbs and tentacle, as seen from below ; 



1, d, the distorted specimen noticed above ; 1, e, structure of the tentacle when very much 

 elongated ; and \,f, its usual appearance when contracted. 



2. Steenstrupia Jlaveola, Forbes. 

 Plate XIII, Fig. 2. 



Umbrella conical, mitrate, transparent, colourless, not exceeding a line in length. Its 

 summit is produced into a mucronated termination, which, though transparent and colourless, 

 appears to be of a different tissue from the rest of the disk, which, besides, is quite smooth, 

 whilst the apex is as if pilose. The margin is contracted as in the last species, and 

 quadrangular, each angle bearing a similar elongated ocellus or tentacle-bulb, in this instance 

 of a fawn yellow colour. One only of these bulbs gives origin to a tentacle, very slender, long, 

 and moniliformly granulated. From the summit of the sub-umbrella, a cord or tube runs to 

 the apex. Its sides are marked by four simple, radiating vessels. The peduncle is very 

 changeable in form : sometimes contracting into a very short, thick, quadrate mass ; at others, 

 assuming the shape of that of Sarsia, but not protruding beyond the disk. It is also of a 

 pale yellowish, fawn colour. The mouth has no produced lips. 



This singular little animal was taken in Penzance Bay towards the close of August, 1846. 

 Plate XIII, fig. 2, a, represents it of the natural size ; 2, b, magnified, its peduncle contracted; 



2, c, with the peduncle extended ; 2, d, the apex of the umbrella ; 2, e, one of the tentacle 

 bulbs. 



