1GG PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



ON THE ANATOMY OF SOME AGNATHOUS MOLLUSCS FROM 

 NEW ZEALAND. 



By It. Murdoch. 



Read 9th November, 1900. 



PLATE XVII. 



1. Khytida Greenwoodi, Gray. PL XVII, Figs. 5 and 6. 



Animal very dark grey in colour, the neck, tail, and sides of body 

 with small, irregularly shaped, flatfish granules, which form irregular 

 rows and extend to the foot-margin ; tail flattened and pointed, 

 it has a well-marked shallow median groove, hut no mucous pore. 

 Foot -sole thrown into transverse wrinkles; sides dark ash -grey, 

 and centre lighter. Labial tentacles small, somewhat triangular in 

 outline. The above description is from specimens preserved in spirits. 

 Suter has given a figure of the animal taken from life (Journ. Malac, 

 vol. vii, 1889, pi. iii, fig. 1). 



The mantle projects slightly over the margin of the shell ; on its 

 under side are developed three small lobes (PL XVII, Fig. 5) ; that on 

 the left {LI.) is very small and narrow, with a small portion of each end 

 free ; the right lobe (r.l.) extends almost to the edge of the mantle, its 

 left edge resting on the sub-central lobe (s.c.l.) ; this last and largest 

 lobe is hatchet-shaped, somewhat fleshy, and projects beyond the 

 mantle edge ; from its base a shallow groove proceeds to the left, 

 passing under the left lobe. 



On opening the body-cavity, the most noticeable feature is the 

 enormous size and muscular development of the buccal mass ; all other 

 organs seem dwarfed by comparison. The posterior end of the mass is 

 drawn down and forward by a powerful ventral muscle ; this muscle 

 is very compact where it leaves the curved end of the mass ; passing 

 forward it spreads out, and largely forms the ventral portion of the 

 outer muscular sheath. Beneath this sheath is the constrictor muscle, 

 which forms a strong wrapper, the fibres transverse to those above ; both 

 muscles are intimately connected by a network of delicate fibres. It 

 appears that the large ventral muscle materially assists in the pro- 

 trusion of the radula ; the contraction of the muscle would have the 

 effect of shortening, or pulling the ends of the mass towards each 

 other, this would compress the transverse fibres of the constrictor 

 muscle, and the contraction of the latter would further assist in the 

 expulsion of the radula. The muscular bands attached to the radular 

 membrane, so far as I could separate them, appear similar to, though 

 less strongly developed than, those in Natalina Caffra, Fer., of which 

 Mr. M. F. Woodward has given an excellent description (Proc. Malac. 

 Soc. Lond., Vol. i, pp. 270-277, PL xvii). The retractor muscle 



