LEUCODORE. 205 



1 . L. ciliatus, front obtusely bilobed ; eyes four, between the an- 

 tennae ; segments 40 to 50. Length 6-8'". Plate XVIII. figs. 1-6. 



Leucodore ciliatus, Johnston in Mug. Zool. Sf Bat. ii. 67. pi. 3. f. 1-6. 



Williams, Rep. Brit. Assoc. 1851, 206. Grube, Fam. Annel. 67. 

 Spio seticoniis, Bluinv. Diet. Ivii. 441, Atlas, pi. iig. 2, copied in 



Griffith's Cuv. xiii. pi. 4. f. 2. Aud. df M.-Edw. Litt. de la France, 



ii. 289. 

 Leucodorum ciliatmn, Sars, Adriat. Havs Fauna, 17. Oersted, Annul. 



Dan. Consp. 39. f. 104. 

 Diplotis hyalina. Garner inTrans. Zool. Soc.voX. ii. pt.ii.99. pi. 20. f. 13. 

 Spio celata?, Dalyell, Pow. Great, ii. 160. pi. 20. f. 21. 



Hab, The littoral region near low water. 



Desc. 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, de- 

 pressed, 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 antennse, 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, nar- 

 row, distinct, the first four with an inferior papillary cirrus on each 

 side, and a brush of retractile bristles ; the fifth with a series of 

 bristles curved like an italic /, 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 bran- 

 chial cirrus originating from the dorsal margin, as long as half 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 of unequal 

 lengths ; under this a bundle of much smaller 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 move- 

 able cilia ; it becomes very small, or entirely disappears on the pos- 

 terior segments, in which the bristles, on the contrary, appear to be 

 longer and more developed. Bristles simple, unjointed. Anal seg- 

 ment 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 sides of the bran- 

 chial 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 certainly dependent on the will of the animal, for I have repeat- 

 edly 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 antennae, 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 



