Dr. W. C. Mcintosh on the Bon fig of certain Annelids. 285 



The inferior appendages of the rest of the body-segment* 

 consist of characteristic hooks — organs, I may add, that have 

 received but scant justice from their artists, with the exceptioti 

 of M. Claparede* and Mr. Agassiz, though the latter appears 

 to have slightly misapprehended their true nature, as he speaks 

 of " a stiff bristle extending from the base of the curve" — which 

 can only refer to the wing of the structure, about to be de- 

 scribed. The figure t of this careful observer, though earlier, 

 is more correct than Mr. Lankester's. When the hook is pressed 

 flatly between glasses (PI. XVIII. fig. 4 a), the crown shows 

 a long tooth in front, with a shorter superior process and a dis- 

 tinct wing ; but the latter, of course, has been altered by pres- 

 sure, as, when viewed under favourable circumstances (fig.4Z>), 

 it has a wing on each side of the crown and upper part of the 

 shaft. Dr. Thomas Williams was in en'or when he assigned 

 a dorsal position to these hooks J. The bristles throughout 

 conform to one type (fig. 5), having a long shaft, somewhat 

 abruptly bent and tapered at the tip, which has a narrow pro- 

 cess or wing on each side. 



The anal segment is fmiiished with a peculiar cup (fig. 6), 

 whose margin does not form a continuous ring, but is inflected 

 and slit in the middle of the dorsal surface. A few minute 

 and motionless cilia are placed round the margin. The papilla 

 of the anal orifice is richly ciliated. The organ does not im- 

 press the observer as being eminently adapted for adhering to 

 surfaces, after the manner of a sucker ; nor have I been so 

 fortunate as to see the animal using it for this purpose. Mr. 

 A. Agassiz and MM. Claparede and De Quatrefages, however, 

 have seen the Annelid employing it for such ; and M . Meczni- 

 koff'§ is another author who mentions that a '^ sucking-disk " 

 is met with in Leucodore. Dr. Williams, again, remarks that 

 the anal segment is expanded with geometrical exactitude into 

 a hollow cone, which acts on the principle of the sucker, the 

 worm " letting down its weight on the part, in order to press 



companying this paper. He said that, instead of one spur, there were 

 several spurs beneath the curved tip. Of course I have found no reason to 

 alter an opinion formed after an examination of specimens from the north, 

 east, and west of Scotland, from the north-east, south, and south-west of 

 England, and from the Channel Islands. Mr. Agassiz and Prof. Kefer- 

 stein, moreover, show only one process ; and though M. de Quatrefages 

 represents at least two beneath the tip of the hook of his Leucodore namta 

 from Br^hat, I am bound to add that many of this distinguished author's 

 drawings are not scientifically accurate. I do not know on what authority 

 my friend made his statement ; and it is to be hoped he will clear up the 

 mystery. * Archiv fiir Anat. u. Phvs. 1861, Taf. 13. 



t Ann. Nat. Hist. ser. .3. vol. xix. pi. 6. fig. 88. 



I Report Brit. Assoc. 1851, p. 208. 



§ Zeitschr. fiir wiss. Zool. Bd. xvi. 

 Ann. & Mag. N. Hist. Ser. 4. Vol.'ii. 20 



