2&G APPENDIX. 



and crystalline (figs. 2, 4). This apparatus is placed within the 

 intestine, is visible only when this is compressed, and is, as I believe, 

 stomachical, having some distant analogy with the proper digestive 

 organs of the Laplysia and Bulla * ; and in confirmation of this view, 

 it may be remarked, that the oesophageal part of the intestine appears 

 to be simple, while the inferior portion exhibits a plaited structure 

 internally (figs. 1, 3). In PI. II. A. fig. 5, this part is represented 

 as being suddenly narrowed, and after descending a little it bends 

 and ascends for some way, when it is again deflected and ends 

 abruptly in the body ; and such undoubtedly were the appearances 

 in the specimen from which the drawing was made, and in others 

 which I have examined ; but such a disposition of parts is rather 

 uncommon, the usual course being for the intestine to descend tor- 

 tuously to the anus. I believe that in the contrary instances, the 

 natural adhesions of the alimentary tube have been ruptured by the 

 compression to which the body had been subjected, and that by its 

 contractions, the intestine was then forced into this unnatural posi- 

 tion ; for that the intestine terminates and opens at the posterior 

 extremity is certain, the contents having repeatedly been seen to be 

 evacuated there through a small pore. While examining specimens, 

 a large portion of the intestine will occasionally be seen rolling itself 

 from the mouth, like a very long proboscis, until perhaps fully one- 

 half of the tube is evolved, — a fact which I also attribute to the 

 compression of the plates of glass ; for I have never observed the 

 worm naturally to evolve a proboscis, though every pains may be 

 taken to force it to do so, by irritation, by keeping it in sea-water 

 until it corrupts, by immersion in fresh water, or in spirits^. 



The intestine lies loose in a distinct abdominal cavity (PI. II. A. 

 fig. 5, and PI. II. B. fig. 1) or canal excavated through the centre 

 of the body. This canal seems to contain besides a grumous fluid, 

 which may frequently be observed moving rapidly up and down in 

 irregular currents dependent on the contractions of the worm or in- 

 testine, and not at all analogous to the currents within the tubes of 

 zoophytes. It is fringed along each side with a close series of vesi- 

 cles or cells formed, in the true Nemertes, apparently by the folds of 

 a membrane, while in the subgenus Borlasia they are separate, and 

 as it were excavated in the parenchyma of the body (PI. II. A.). 

 The resemblance between this structure and what have been called 

 ccecal ajjpendaffes in some allied worms is obvious |, though not very 



* Nemertes, mihi, is evidently the same as the Prostoma of Duges. My sto- 

 mach is his mouth. See the Edinb. Journ. of Nat. and Geog. Science, iii. 379. 



The circulating system seems to be nearly the same as in the Nais proboscidea, so 

 far as I am able to judge by an examination of the figure of this given by Gruit- 

 huisen in the Nov. Act. Acad. Nat. Cur. tom. xi. pi. 35. 



t In some cognate species, Otho Fabricius observed the intestine to be extruded 

 when no compression was used, but still under circumstances easily reconcileable 

 with our explanation. " De orificio antico infero tnbulum pallidum inagone mor- 

 tis exserit : " i. e. Planaria rubra, Faun. Groenl. p. 324 ; also p. 325. 



X Comi)are our figures of this structure with that of the Diplozoon para- 

 doxum of Nordmann in Ann. des Sci. nat. xxx. 382. pi. 20. This figure, on a re- 

 duced scale, is copied into the Cyclop, of Anat. and Physiology, i. 654. f. 328 ; 



