51 



The following is Dr. Johnston's description, as given in the 

 British Museum Catalogue of the British Non-Parasitical Worms, 

 page 205 : — 



Leucodore ciliatus. 



" Worm from 6 to 8 lines long, linear-elongate or slightly tapered 

 to the tail, somewhat quadrangular, of a yellowish or flesh colour, 

 with a dark red line down the middle. Head small, depressed, 

 in the form of a short cylindrical proboscis, encircled with a 

 raised hood or membrane. Mouth edentulous, eyes four, minute, 

 placed in a square at the base of the antenna?, which are more 

 than a fifth of the length of the body, tapered, wrinkled, and 

 clothed along their inferior sides with short cilia. Segments 

 numerous, narrow, distinct, the first four with an inferior papil- 

 lary cirrus on each side, and a brush of retractile bristles ; the 

 fifth with a series of bristles curved like an italic J\ obtuse, not 

 capable apparently of being protruded like the others, and having 

 rather a more ventral position ; the following segments have on 

 each side an obtuse branchial cirrus, originating from the dorsal 

 margin, as long as half of the diameter of the body, held either 

 erect or reflected across the back to meet its fellow on the mesial 

 line ; beneath it a small mammillary foot, armed with five or six 

 sharp slightly curved bristles (crotchets ?) with a small conical 

 cirrus with a still more ventral position. The branchial cirrus is 

 clothed on its lower aspect with rather long moveable cilia ; it 

 becomes very small or entirely disappears on the posterior seg- 

 ments, in which the bristles, on the contrary, appear to be longer 

 and more developed. Bristles simple, unjointed. Anal segment 

 conformed into a circular cup or sucker, in the centre of which 

 the anus opens by a small round aperture. In this worm the 

 cilia, which cover the under side of the branchial processes, are 

 remarkable for their size and length, for they can be seen with a 

 common magnifier fanning the water with equal and rapid beats, 

 and driving the current along their surface. Their analogy with 

 the cilia of Zoophytes is obvious ; but here their motion is cer- 

 tainly dependant on the will of the animal, for I have repeatedly 

 seen it begin and stop, and be again renewed after an interval of 

 repose, and again be checked in a manner that could leave no 

 doubt but that the play of the organs was entirely voluntary. 

 The cilia of the antenna?, notwithstanding the larger size of the 

 organs, are less than half the length of those of the branchiae. 



Leucodore ciliatus lives between the seams of slaty rocks, near 

 low-water mark, burrowing in the fine soft mud which lines the 

 fissures. Its motions are slow. When placed in a saucer it keeps 

 itself rolled up in aji imperfectly circular manner, lying on its 

 side, and the painful efforts made to change its position, with 

 little or no success, show too plainly that it is not organised to 

 creep about like the Annelides errantes, but, on the contrary, that 



