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XXXI. Obsenatiotia on the " Bitentaculate Slug " of Neio Zealand (Limax bitentacu- 

 latus, Quoy and Gaimard ; Janella antipodarum, Gray ; " Aneiteum Slug " ?, Mac- 

 donald). By Charles Knight, Esc[., F.L.S. 



Read June 2nd, 1859. 



Auckland, New Zealand, 



27th December, 1858. 



Dear Sir, 

 1 HAVE lately compared Mr. J. D. Macdonald's observations on the Bitentaculate Slug 

 found at Aneiteum (Annals and Mag. Nat. Hist. 2 ser. xviii. p. 38, 1856) and Dr. Gray's 

 description of Janella antipodarum (Annals and Mag. Nat. Hist. 2 ser. xii. p. 414, 1853) 

 with the living Gasteropod found in New Zealand, and trust that the following notes 

 and the accompanying drawing will interest the members of the Society. 



The New Zealand moUusk is little more than an inch in length. The mantle (?) covers 

 the whole of the upper surface. The space which Dr. Gray describes as existing between 

 the edge of the mantle and the foot, is on the under surface of the animal ; so that the 

 edge of the mantle forms the ovitline of the body as seen from above. The mantle (?) is 

 mottled with light-coloured spots, the larger of which are at regular intervals, and are at 

 times elevated above the surface in sharp conical points (fig. 14). The " raised margin " 

 of Dr. Gray's description is due to the effects of alcohol. 



In alcohol the animal becomes subcylindrical, and answers to the description of 

 Dr. Gray and to that of Lamarck (Anim. sans Vert. 2nd ed. vol. vii. p. 723, Li/max liten- 

 taculatus, Quoy). 



The aperture of respiration {d, fig. 3) is on the right side of the slightly depressed roof 

 of the pulmonary sac. There are four small, semitransparent, calcareous (?) granules in 

 the anterior wall of the pulmonary sac (fig. 13) ; and immediately anterior to the sac is a 

 small foramen (a, fig. 3), affording passage to a fltiid which flows in pulsatory waves over 

 its roof. Generally this pulsatory movement occurs at regular and frequent intervals ; 

 and the wave extends aroimd the pulmonary aperture, as if a limpid fluid were pro- 

 pelled under the glutinous secretion which covers and protects the body of the mollusk. 



The buccal mass is armed above with a single horny plate or tooth (figs. 7, 8). In feed- 

 ing, the animal forces forward the buccal mass, and scrapes or hoes up with the horny 

 plate the surface of the substance it is feeding on. 



The lingual sac, instead of being furnished with the single, symmetrical, tubular 

 appendage of the common Slug of these Islands, has posteriorly two delicate, plicated, 

 convolute appendages armed with transverse rows of dental processes (figs. 11, 12). The 

 sac itself is furnished with a complete armature of rasps (figs. 9, 10) placed in numerous 

 transverse parallel rows, which meet in the median line at a very obtuse angle. Each rasp 

 has several minute teeth, and is set diagonally in the row, as are also the spine-like plates 

 from which the minute rasps project (fig. 10). 



