338 E. RAY LANKESTER. 



grow much bigger^ as most of my specimens died -witliin a 

 quarter of an hour after their birth. 



Its shape bears a rude resemblance to Pedalion shorn of 

 its rudder, but it swims very differently, constantly spinning 

 round its own length like a joint on a spit. It can jerk its 

 side arms, and it uses them in this way to free itself from its 

 shell; but the arm bears only a long bristle or two, not 

 fringes like those of its mother. 



It possesses also longitudinal muscles for retracting the 

 head, and it can do this so far as to bring its two eyes down 

 into the centre of its body. On the death of one of them I 

 observed the (usually inverted) penis protruded to a length 

 quite equal to that of half the animal. 



Pedalion's stomach, with its two oval glands and oeso- 

 phagus, is similar to those of Triarthra, and its mastax 

 (flattened by the compressorium) is shown in fig. 6. Fig. 7 

 is an enlarged view of the retractile antenna shown, with its 

 muscle [q), at (r) in fig. 2. 



The two ciliated projections at the end of the animal are 

 of the most variable length in different individuals, in some 

 being scarcely visible ; they are always very short in the 

 newly hatched females. They are, I believe, merely another 

 form of the secreting pincers (as they are termed) of Hyda- 

 tina, Syncha3ta, &c., for I have seen a dying Pedalion moored 

 by its own viscid secretion to some alga?, and slowly swim- 

 ming in a wide circle by help of this natural rope, which in 

 this case distinctly originated in an extremity of one of the 

 ciliated projections. The use of the cilia, I imagine, is to 

 keep the viscid extremities clear of floating atoms. 



Remarks on Pedalion. By E. Ray Lankester, M.A. 



The form which Dr. Hudson has made known in the pre- 

 ceding paper is one which cannot fail to arrest the attention 

 of all zoologists at the present time, who are interested in 

 speculations upon the genealogy of the animal kingdom. Dr. 

 Hudson had the great kindness to send me living specimens 

 of his rotifer, and I am, therefore, able to join my testimony 

 to his, and can speak to the accuracy of his drawings and 

 description. In addition to its ciliated discs Pedalion pos- 

 sesses four pairs of movable appendages — two median dorsal, 

 tAvo median ventral, two right lateral, and two left lateral. 

 All these have fibres of transversely striated muscular tissue 

 inserted at points in their walls, by which they are moved. 



