332 Mr. Jeffreys on the Animal of Stilifer Tartoni. 



scription, — viz. Stilifer Broderipii, S. Cumingii, S. fastigiatus, 

 and S. solidus of Adams's ' Genera/ and S. pjjramidalis of 

 Mr. Reeve. In the British Museum is an unnamed Stilifer 

 from Port Natal, said to have been found attached to the mouth 

 of a Starfish. 



It is not improbable that some of the species enumerated in 

 the 2nd section, having an elongated spire, may belong to Eu- 

 lima or Niso, instead of to Stilifer. 



I am not aware of any fossil species having been discovered. 



I will now give the result of my examination of the animal of 



S. Thirtoni, from notes made at the time. 



Body white, and delicately stippled ; the whole of the upper 

 surface is covered with microscopical and extremely short 

 cilia, which are in constant motion; these cilia are arranged 

 in scale-like bunches, and by their action produce a circu- 

 lating current. 



Mantle thickened at its edges, and spread over the lower part of 

 the shell, so as to form a disk. 



Pallial fold, or branchial opening, on the right-hand side, form- 

 ing a canal which terminates in an oval or roundish hole. 



Head-lobes rounded and flattened, nearly transparent, one on 

 each side a little below the snout or mouth. 



Snout rather long when extended, but usually folded inwards 

 and trunk-like, slightly bilobed, and placed between the 

 tentacles and the foot. 



Tentacles club-shaped, somewhat compressed, thick, and rather 

 long, sometimes expanded at the tips, which are blunt and 

 widely diverging, but united at their bases ; they are more 

 or less strangulated or constricted, usually at about one- 

 fourth of the distance from their bases. 



Eyes exceedingly small, seated on the neck or back of the head, 

 at some distance behind the tentacles. 



Foot tongue-shaped and elongated, bulbous and forming a 

 creeping-disk in front, somewhat tubular in the middle, 

 and tapering to a fine point behind ; the sole, or under 

 part, is slit in the middle for more than three-fourths of 

 its length, the opening or commencement of the slit being 

 near the bulbous part and oval. 



Male organ spiked, and resembling an auxiliary tentacle. 



Habitat, Whalsey Skerries, East Shetland, about 40 miles from 



land, in 80 fathoms, sandy bottom, on an Echinus Drobachiensis. 



A pair of the Stilifer were attached to the sea-egg on its upper 



surface, between the spines near the vent or anal orifice ; and 



the same part was also covered with about forty clusters of 



