16 PLEUROPHYLLIBIID^E. 



Specimens which Mr. Thompson kindly sent me from 

 Weymouth in a bottle of sea-water with Confervse, were 

 dark purplish-brown with minute round spots of yellow 

 and a streak of the former colour on the tail ; the sides 

 of the front portion of the mantle, as well as the hinder 

 portion and the sides of the tail, were buff; the eyes 

 were indistinct, deeply sunk in the outer skin, and not 

 encircled by rings; the mouth was furnished with a 

 pair of large triangular lips or lobes; the branchial 

 plumes lay on the right-hand side of the vent, which 

 was placed in the middle of the hinder edge of the 

 mantle ; and the whole substance of the body was 

 parenchymatous. They were extensile and exceedingly 

 active. The figures given by Messrs. Adams and those 

 in the ' British Mollusca' are not satisfactory. The dis- 

 coverers of this singular little mollusk suspected that 

 Pelt a of Quatrefages may be the young before the 

 branchial apparatus is developed. If that be the case, 

 why was Runcina substituted for the older name ? 



Family V. PLEUROPHYLLIDI'IDjE, 

 H. & A. Adams. 



Body oblong, depressed, fleshy : mantle of a somewhat 

 coriaceous texture, covering the upper part of the body and 

 notched in front : head short, broad, and forming a triangular 

 lobe in front of the mantle ; it is mostly furnished with plaited 

 lips and a pair of very strong horny jaws : odontophore broad ; 

 teeth numerous, arranged in cross rows : tentacles "2, very 

 small, conical or club-shaped, close together, retractile, each 

 in a socket within the pallial notch : foot elongated, somewhat 

 narrower than the mantle, slightly indented in front and 

 abruptly pointed behind : gills placed under the edges of the 

 mantle on the binder two-thirds of the body, and arranged in 



