290 APPENDIX. 



common in the genus. Body linear and narrow, from 3 to 6 inches 

 long, a line or so in breadth, smooth and compressed. Anterior ex- 

 tremity rounded, obscurely marked with a red spot over the site of 

 the heart. In the * Zoological Journal ' I have described this species 

 as having only two eyes ; but as this appears to be a mistake, or at 

 least not constant in the species, it has become necessary to alter its 

 designation. 



When pressing a portion of the body between the plates of glass, 

 I have occasionally seen some bodies escape, of a curved fusiform 

 shape, acute at both ends, and marked towards one of them with a 

 pale circular spot. They have shown no signs of life, nor can I say 

 what they are, though it has occurred to me that they may be em- 

 bryo-young, and that the worms may in fact be ovo-viviparous. 



Borlasia octoculata (page 21). 



Body linear, narrowed posteriorly, 3 inches long, and about ith 

 of an inch broad, compressed, of a light reddish-brown colour, with 

 a darker spot in front over the hearts. Eyes six or eight, and in 

 some specimens I have seen seven, three on one side, and four on the 

 other. It appears, therefore, that the number of the eyes, on which 

 MiJller and others have reckoned confidently as a good and invariable 

 character, is not to be implicitly relied on. 



Borlasia purpurea (page 21). 



Worm 2 or 3 inches long, smooth and glutinous. From the dark- 

 ness of its colour, the spot indicating the position of the heart is 

 scarcely visible until the body has been compressed. The number 

 of eyes is the same as the preceding, and liable to the same variety. 

 In this species the ova were distinctly seen to be contained within 

 the csecal vesicles, which, when compressed, assumed a pyriform 

 shape, ha\ing the slender end toward the intestines. 



The young are of a wood-brown colour with a pale hinder extre- 

 mity. In some of them there are four eyes only. The usual num- 

 ber is six, and when the creature is creeping in the water, they 

 appear like minute miliary or prominent granules on each side. The 

 genital aperture is elliptical, and placed immediately behind the red 

 spot produced by the ganglia. The worm can swim at the surface, 

 slowly, in a reversed position. 



Borlasia gesserensis (page 22). 



" Length 3^ inches ; figure nearly linear ; extremities obtuse ; six 

 or more black specks around the anterior margin. A slit below in- 



Nemertes of Cuvier, equally unnecessary, and as originally applied altogether in- 

 admissible. Because it commemorates a worthy naturalist, Dr. William Borlase, 

 author of the * History of Cornwall,' I rejoice in being able to affix it to a group 

 hitherto uncharacterized. 



