Dr. W. C. M'Intosh on the Boring of certain Annelids, 283 



this species (in all probability), which he termed 8j^io seti- 

 cornis. He observed that the tentacles, when seizing a frag- 

 ment of oyster, attached themselves to it " not by winding 

 themselves round it, but by simple adhesion, as if they were 

 studded with numerous suckers and hooks, like the arms of the 

 cuttle-fish." This prehensile apparatus " consists of numerous 

 large papillaa thickly crowded together along the borders of 

 the tentacles," each having an " acuminated soft cilium or 

 spine." On forcibly pressing the tentacle, " the spine-bearing 

 papillas burst, and there issues from each of them a pear- 

 shaped capsule (trichocyst) which, again, on rupture, dis- 

 charges a multitude of acicular spicules." He likewise states 

 that the tentacles are furnished with " a ciliated band running 

 from the tip to the base," but does not point out the actual 

 disposition thereof. In his drawing of the tentacle (fig. 18) 

 the papillae are ranged along each side of the organ from base 

 to apex. 



When the tentacle is extended, as in its ordinary motions 

 (PI. XIX. fig. 1), there is little or no appearance of wrinkles. 

 A very considerable alteration, however, ensues on placing the 

 animal, even without irritating pressure, between glasses, and 

 certainly much more so if the tentacle itself is removed by 

 violence. The ciliated groove along the inner border, like the 

 rest of the organ, is minutely granular, especially towards the 

 tip, the latter, on the slightest contraction, assuming a minutely 

 warty aspect (fig. 2). Besides the long cilia which cover the 

 furrow, there are various motionless hairs along the opposite 

 or exterior border of the organ, as indicated by Prof.Keferstein, 

 and which are also present on various other parts of the animal. 

 The wrinkling of the tentacles in most views is very marked, 

 the whole organ being crossed by transverse seams, between 

 every two of which a series of very distinct temporary papillae 

 occur at the edge, which papillge sometimes do possess a mo- 

 tionless cilium or ^' spine," and are more likely to do so under 

 paralyzing pressure ; but the appearance shown by Dr. Wright 

 is the result of injury, and not a natural interpretation of their 

 anatomy, however closely his outline may indicate what he 

 saw. These temporary papillae, in common with the entire 

 surface of the furrow, certainly present a streaked appearance ; 

 but such is due to the compressed cilia ; and I have never been 

 able to see the remarkable " trichocysts " and their acicular 

 contents as described by this ingenious naturalist, to whose 

 observations I gave due respect by repeated examinations. 

 Circular cells filled with minute granules often escaped through 

 the delicate epiderm of the pressed organ, together with mi- 

 nute granules and swarms of discarded cilia ; but there was no 



