532 Miscellanea Zoologica. 



never observed the worm naturally to evolve a proboscis, though 

 every pains may be taken to force it to do so, by irritations, by keep- 

 ing 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. XVII. 

 Fig. 5, and PI. XVIII. Fig. 1,) or canal excavated through the cen- 

 tre 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 sub-genus Borlasia, they are separate, 

 and as it were excavated in the parenchyma of the body, (PI. XVIII.) 

 The resemblance between this structure and what have been 

 called ccecal appendages in some allied worms is obvious, t though 

 not very exact, for they are not produced from, nor in organic con- 

 nection with the alimentary canal, as is manifest from their remain- 

 ing unaffected during the motions of the latter, which moreover may 

 be removed entirely from the body without bringing with it, or 

 tearing away, the presumed coeca. These are always full of some 

 opaque matter in the Nemertes, and some observations lead me to 

 believe, that it varies in intensity at least according to the nature of 

 the animal's food, whence I conclude they belong chiefly to the di- 

 gestive system ; while the ova appear to be developed in their in- 

 terstices, and in the space between them and the skin, (PI. XVII. Fig. 

 2.) But in Borlasia the cceca are more distinctly vesicular and iso- 

 lated, and although the depth of colour of their contents varies also^ 

 yet they are usually clearer and paler than the surrounding paren- 

 chyma, or as it were empty, and I have plainly seen in them, not 

 often, indeed, oviform bodies, which again have not been detected in 

 the interstices, (PI. XVIII. Fig. 3.) We seem, then, to have com- 

 bined in them a duplicity of function, — they are both nutrient and 



" In some cognate species, Otho Fabricius observed the intestine to be ex- 

 truded when no compression was used, but still under circumstances easily re- 

 concileable with our explanation. " De orificio antico infero tubulum pallidum 

 in agone mortis exserit -." i. e. Planaria rubra, Faun. Groenl. p. 324 ; also p. 325. 



■J- Compare our figures of this structure with that of the Diplozoon para- 

 doxum of Nordmann iii Ann. des Sciences Nat. V. xxx. p. 382, pi. 20. This 

 figure, on a reduced scale, is copied into the Cyclop, of Anat- and Physiology, 

 i. p. 654, fig. 328 ; and into Kirby's Bridge water Treatise, pi. 1. B. fig. 4. 

 The comparison may be usefully extended to the Annelides, Cyclop, of Anat. 

 and Phy. i. p. 169, fig. 70 ; Roget, Bridgew. Treat, ii. p. 103, fig. 260; and to 

 the Tarda, Ibid. ii. p. 83, fig. 247. 



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