294 Dr. W. C. Mcintosh on the Boring of certain Annelids. 



CErsted and Mr. Lankester) has clearly made out another 

 European species ; for I consider Leuckart's Leucodore mu- 

 ticum * a somewhat inaccurately described L. ciliatusj John- 

 ston. The possession of only two eyes, and the fact that the 

 great hooks occur on the " sixth " segment of the body, and 

 are three-toothed, characterize the L. nasutus of M. de Qua- 

 trefages. The author states that the anal segment terminates 

 in a flattened cup, which permits the Annelid to attach itself 

 to solid bodies ; and his figure shows no split in the margin. 

 If the latter arrangement is correct, then the previous cha- 

 racters may hold. It is also but fair to remark that speci- 

 mens occur at St. Andrews with two eyes, and even with one 

 only, and that the anterior pair in all, being on a lower level, 

 are less easily seen from the dorsum than the posterior. The 

 same may be said of L, audax and its circular cup. More- 

 over, as the latter assumes somewhat altered appearances in 

 those whose tails are regenerating, some caution is needed in 

 basing specific differences thereon. His L. Fahricii rests, as 

 a species, upon characters that require further elucidation ; 

 and the remarks on L. ciliata are based on Dr. Johnston's 

 description; and hence the author is misled as to the structure 

 of the hooks of the sixth segment (fifth of the body), which 

 really, as already mentioned, have a secondary spur or process. 

 L. duhia is also founded on insufficient data. Lastly, there 

 can be little doubt that the Polydora cornuta described by 

 M. Clapar^def, and given by M. de Quatrefages as the type of 

 a new genus, is nothing more than L. ciliata. The want of 

 scientific accuracy in the figures of the genus in the ^ Anneles ' 

 renders identification difficult. 



EXPLANATION OF THE PLATES. 



Plate XVIII. 



Fig. 1. Leucodore ciliata, Johmst. ; enlarged under a lens. 



Fiff. 2. Great hooks of the fifth segment of the body : a, as usually seen 



in the separated and perfect organ under pressure ; b, a more 



complete view, as obtained in the living animal or in a favourable 



spirit preparation. X 700 diameters. 

 Fig. 3. Spear-tipped bristles accompanying the former. X 700 diams. 

 Fig. 4. Hooks of the posterior region of the body : a, pressed between 



glasses J b, seen in front, so as to exhibit both wings, x 700 



diams. 

 Fig. 5. Front and side view of two of the bristles of the same species. 



X 700 diams. 

 Mg. 6. Caudal segment and its cup. x 210 diams. 



Plate XIX. 

 Fig. 1. Tubes erected by Leucodore at the apertures of its tunnel. The 



* "Zur Kcnntniss der Faima von Island," Arcliiv fiir Naturges. 1849, 

 p. 200, Taf. in. fig. 12. 



t Recherehes Anat. sur lee Annelidcs, Turb. &c. 1861. p. 47, ct op. cit. 



