PROBOSCIS. 105 



seem to be analogous to the " stabformigen Korperchen" of Professor Kolliker, 1 and other 

 investigators of the structure of the Annelida. In the Carinetta from Balta, the proboscis 

 proceeds from the tip of the snout in the usual manner, but instead of the posterior end 

 diminishing insensibly into the long muscular fasciculus, the organ divides into two nearly equal 

 trunks (Plate XXI, fig. 9), each about as large as the entire portion, and terminating in a some- 

 what abrupt and dilated end, to which a long muscular ribbon is attached. The wall of this 

 peculiar proboscis, so far as I could make out from the single and rather unfavourable example, 

 had the following structure : — A circular layer showing a few granules on the outer margin in 

 transverse section occurs externally ; within is a powerful and apparently continuous longitu- 

 dinal muscular coat, from the inner surface of which the granular papillary mucous lining 

 projects. The inner or free margin of the latter is comparatively smooth, a result probably due 

 to the minuteness of the papillae. Each limb of the fork has the same structure as the 

 anterior region, and the thick longitudinal coat, after bending inwards at the posterior end of the 

 dilated termination, becomes continuous with the muscular ribbon. The proboscis thus differs 

 from the ordinary form in the Carinellidce in the bifurcation, and in having no distinct circular 

 coat within the longitudinal. It has no closer analogy with any other type. 



In Cephdothrios the papillae of the proboscis are acicular, and longest anteriorly 

 (Plate XVIII, fig. 15). In transverse section the walls present a simpler structure than in 

 Lineus ; but, though in the living animal an external circular and an internal longitudinal muscular 

 coat are apparent, the tissues become so confused after mounting, that I have not satisfactorily 

 unravelled them. 



Under the action of powerful irritants, such as alcohol, the Lineidce detach, in their spasms, 

 both the anterior and posterior connections of the proboscis at once, so that the extruded organ 

 remains in its ordinary condition when expelled, and is not everted. In Cephdothrios, again, it 

 sometimes ruptures near the ganglia, and is drawn backwards by the ribbon of attachment and 

 its own elasticity ; the animal apparently being unaffected by the injury, which regeneration soon 

 repairs. I have never seen the worm use the proboscis for any purpose ; and though M. van 

 Beneden has observed it extruded in Cerebratulus (Erstedii {Lineus bilineatus), and threatening 

 its prey, I fear it could not do much harm. The lifelike vermicular motions of this muscular 

 tube, both in situ and when cast off, have misled Mr. Beattie and others, so that they 

 described the organ as a young animal, and the possessor as viviparous, or even considered 

 the expelled portion a parasite. This is at once apparent on examining Mr. Beattie's special en 

 of the supposed young animal in the British Museum. The proboscis is reproduced in the same 

 manner as in the Enopla ; and the discarded organ, if not ejected, may be seen floating in the 

 proboscidian cavity amidst much granular debris. Sir J. Daly ell states that the usual colour of 

 the proboscis in Lineus marinus is vivid red ; our specimens have generally had white or faintly 

 pinkish organs. 



M. van Beneden does not mention the tissues to which the muscular retractor of the pro- 

 boscis is attached in his Nemertes communis, and speaks of it as suspended freely in the cavity of 

 the body, like the digestive tube of the Bryozoa. A further remark with regard to the organ in 



1 Vide c Kurzer Bericht iiber einige im Herbst 1864 an der Westkuste von Schottland/ &c, pp. 12, 

 et seq. 



14 



