538 Miscellanea Zoologica. 



9. N. rufifrons, of a yellowish colour verging on rose-red anteri- 

 orly ; mouth dark red ; eyes none ; body very slender. (PL 

 XVIII. Fig. 5.) 



Hab. Under stones between tide-marks, in Berwick Bay, fre- 

 quent. 



When fully stretched out in creeping, this worm is fully two inches 

 long, but very narrow and filiform, or rather tapering to a point 

 posteriorly ; it is of a yellowish colour for the greater part, but the 

 anterior extremity is a rose-red, while the apex or mouth forms a 

 dark red speck. When slightly compressed between plates of glass 

 the intestine may frequently be seen unrolling itself from the cir- 

 cular and terminal mouth in the manner that some annelidans un- 

 roll their proboscis. The worm will thus sometimes nearly disem- 

 bowel itself. The intestine is white, round and filiform, without 

 any appendage. 



Explanation of Plates. 



Plate XVII. Fig. 1, Nemertes gracilis of the natural size. 

 1. * Anterior portion of the same magnified ; Fig. 2, 2, N. lactiflo- 

 rea, both figures of the natural size. 2. * Anterior portion mag- 

 nified. 2 * * Caudal extremity magnified, shewing the ova exte- 

 rior to the cceca ; Fig. 3, N. lactiflorea, var. brunnea. 3. * 

 The head magnified ; Fig. 4, N. quadrioculata, natural size ; 

 Fig. 5, N. melanocephala, natural size. 5. * The same magnified ; 

 Fig. 6, N. pulchra, natural size. 6. * The head of the same mag- 

 nified. 



Plate XVIII. Fig. 1, 1, 1, Nemertes (B.) olivacea, of the natu- 

 ral size. 1. * The anterior and middle part magnified. 1* * Em- 

 bryo young ? of the same contained in the body of some specimens. 

 Fig. 2, Nemertes (B.) octoculata, natural size. 2. * The anterior 

 portion magnified ; Fig. 3, Nemertes (B.) purpurea, natural size. 

 3. * The head, and a portion of the middle, and the tail magnified, 

 shewing the ova within a kind of vesicle. Fig. 4, Nemertes (B.) 

 rufifrons, natural size. Fig. 5, A portion of the anterior extremity 

 magnified. 



Of the wood-cut Figs. 1, 2, represent the stomach and a portion 

 of the intestine of Nemertes lactiflorea ; 3, and 4, of the N. pul- 

 chra ; 3, shewing it previous to being compressed, 4, after being 

 compressed between plates of glass. 



