Acmaxt.l GASTROPODA. 69 



9. Acmaa Helmsi, E. A. Smith, 1894. Plate 7, fig. 3. 



Acmceu Helmsi. E. A. Smith, P. Mai. S., i, 1894, 58, pi. 7, f. 4, 5; Suter, 

 P. Mai. S., vii, 1907, 324. 



Shell small, depressed cap-shaped, almost smooth, bluish-grey, 

 ornamented with numerous radiating reddish-black narrow lines. 

 Apex subterminal, anterior slope slightly concave, posterior slope 

 convex, arcuate. Interior greenish ; central area white, with a few 

 rufous spots ; margin but faintly crenulate ; border narrow, yellow, 

 marked all round with reddish-black rays. (Translation of E. A. 

 Smith's diagnosis.) 



Length, 11-5 mm. ; breadth, 9 mm. ; height, 4 mm. 



Dentition unknown. 



Type in the British Museum. 



Hab. Grey mouth, type (R. Helms) ; Cape Egmont (R. Murdoch). 



10. Acmaea parviconoidea, Suter, 1907. Plate 5, fig. 13. 



Ac-mat parviconoidea, Suter, P. Mai. S., vii, 1907, 321, pi. 27, f. 22-25. 

 A. conoidea, Quoy and Gaimard : Hutton, T.N.Z.I., xv, 132 ; P.L.S. 

 N.S.W., ix, 373, not of Quoy and Gaimard. 



Shell small, thin, highly conical to depressed conoidal, oval, with 

 very fine radiate strise and irregular brown bands. Good specimens 

 show indistinct and very low radiate riblets, corresponding to the 

 brown lines, and under a strong lens fine and close radiate threads 

 can be distinguished, crossed by still finer concentric growth-lines ; in 

 most examples this sculpture is lost, the shells being eroded. The 

 colour of the type is light brown, with a few dark concentric bands 

 and spots around the margin ; the much more common conoidal 

 form is dirty-white, with radiate brown or black lines which reach 

 up to the apex, or, more often, ornate only the lower half of the shell, 

 the upper half being tessellated with black and white. Apex at about 

 the anterior third, directed forward and sharply pointed, but very 

 often rounded off by erosion ; the slopes are broadly convex posteriorly, 

 straight or distinctly concave anteriorly. Interior light brown to 

 white ; central area dark brown, with patches of lighter colour, 

 sometimes quite white ; margin sharp, with brown dots and lines. 



Length, 4-5 mm. ; breadth, 4 mm. ; height, 3-5 mm. (type). 

 Length, 9 mm. ; breadth, 7 mm. ; height, 4 mm. (the common form). 



Dentition. Hutton, T.N.Z.L, xv, 127, pi. 15, f. K ; Suter, P. Mai. S., 

 vii, 322, pi. 27, f. 24, 25. 



Type in the Canterbury Museum, Christchurch. 



Hob. The type is from Sumner, near Christchurch, where it is 

 found living on rocks between clusters of Modiolus ater ; Heathcote 

 Estuary ; Lyttelton ; Oamaru ; Cape Saunders ; Greymouth ; Tau- 

 maki Island ; Cook Strait ; Evans Bay, Wellington Harbour ; East 

 Cape Lighthouse ; Auckland Harbour ; west coast, between Manukau 

 and Kaipara ; Bay of Islands ; Chatham Islands. 



