546 GASTROPODA. [O pitthobranchia. 



of conchm. no calcareous layer being noticeable. Colour light brown, 

 darker at the centre, somewhat shining. Apex elevated, recurved, 

 forming a roundish tubercle. Right side auriculated, descending in a 

 slightly convex line, base regularly rounded, left margin shorter than 

 the right, the upper margin obliquely descending and lightly ex- 

 cavated. 



Diameter, 17 mm. ; height, 28-5 mm. (type). 



Animal a dark brown (kelp-colour), spotted all over with grey- 

 pepper-coloured spots. The edges of the lower lobe of the mantle 

 marked evenly with alternate darker brown and grey. The lobe 

 covering the shell striped with grey, all of which stripes point to, and 

 narrow towards, the apex of the shell. Posterior sides of tentacles 

 also a peppery-grey colour. Length, about 127 mm. (Mein.) 



Type lost. 



Hab. Waimarama, Hawke's Bay, type (Meinertzhagen) ; Mango- 

 nui ; Bay of Islands ; Brighton, Otago. 



Remark. As pointed out by Mr. Hedley (P.L.S. N.S.W., 1905, 

 537). the shell does not differ from T. norfolkensis, Sowerby, from 

 Port Jackson, and the colouring of the animal also seems to be very 

 similar in the two species. The animals, however, will have to be 

 carefully compared before we can be quite certain about the identity 

 of the two species. 



3. Tethys venosa, Hutton, 1875. Plate 23, fig. 13. 



Aplysia venosa, Hutt., T.N.Z.I., vii, 1874 (1875), 279, pi. 21 ; J. cle Couch., 

 1878, 41 ; M.N.Z.M., 123. Tethys venosa, Hutt., Man. Conch. (1), xvi, 

 98, pi. 59, f. 39 ; Index, 68. 



Shell membranous, the epidermis pale straw-colour. Apex rather 

 coarsely concentrically striated, the rest of the shell smooth and 

 polished. 



Diameter, 25-5 mm. ; height, 31-5 mm. 



Animal yellowish-brown, veined with dark brown, about 6 in. 

 (= 152 mm.) long. 



Type in the Otago University Museum, Dunedin. 



Hab. Wellington ; Sumner, near Christchurch. 



Genus 2. NOTARCHUS, Cuvier, 1817. 



Notarchus, Cuvier, " Regne Animal," ii, 398. Type : N. indicus, Schweigger. 

 Bursatella, BlainvUle, in Ferussac, 1822. Adesia, Rang, 1828. Stylo- 

 cheilus, Gould, 1852. 



General form long-ovate or fusiform, plump in the middle. Ten- 

 tacles, rhinophores, eyes, and genital groove as usual in the family. 

 Pleuropodial lobes broadly united behind over a large gill-cavity, 

 their anterior ends contiguous, free margins short, contiguous ; the 

 dorsal slit subcentral and short. Mantle membranous, small, not 



