SUTER: ACMiEIDiE OF NEW ZEALAND. 323 



there are sometimes two short posterior marginal rays ; round the apex 

 a few concentric rows of small, oval, vivid blue spots. Inside white, 

 spatiila purplish-black, sending off four to nine rays towards the margin. 

 The adult shell has lost all its sculpture ; the colour - markings on 

 a whitish ground consist of two lateral and two posterior black rays, 

 descending from the apex and extending only over a short distance ; 

 the margin is adorned with numerous short, black lines. Inside 

 yellowish-white, the central area occupied by the now distorted star 

 of purplish-black ; margin sharp, with a broad border, rayed with black. 

 Length 10, breadth 7, height 5 mm. Adult specimen. 

 ,, 4, ,, 3, ,, 1-5 ,, Young specimen. 



Dentition unknown. Type in my collection. 



Uab. — Titahi Bay, Cook Strait. Type (Miss M. Mcstayer) : 

 Taumaki Island, in 10 fathoms (Captain Bollons). 



Sand collected by Miss M. Mestayer at Titahi Bay contained a number 

 of young specimens of what I first took to be a new species. However, 

 I found one example of an adult shell which unmistakably showed, 

 though distorted, the central black star, but otherwise it cannot be 

 separated from A. parviconoiclca. The fact that the very same young 

 shells were dredged by Captain J. Bollons in 10 fathoms goes to show 

 that these small forms live in the laminarian zone, where they most 

 likely never attain a much larger size than that indicated; but 

 specimens reaching the littoral zone will no doubt grow to the full 

 size of the species with its most constant characters. It was most 

 fortunate that I got this adult shell, otherwise I should not have 

 hesitated to describe the young shell as a new species. 



11. ACM^A DiEDALA, n.u. PI. XXVII, Figs. 30-32. 

 Acmma flammea, Q,. & G. : Hutton, Trans. N. Zeal. Inst., vol. xv, 

 1882 (1883), p. 132; Proc. Linn. Soc. X.S. Wales, vol. ix, 

 p. 373; Index Fauna3 Nov. Zeal., p. 85; not of Quoy & Gaimard. 



Shell small, oval, depressed, pellucid, radially netted with brown, 

 apex anterior. The sculpture consists of numerous microscopic radiate 

 stria?, crenulated by fine incremental lines. Colour light yellow ; 

 numerous light-brown radiate lines give, by anastomosing the whole 

 surface, a net-like appearance. Apex anterior, at about the anterior 

 eighth, slightly pointed ; anterior slope concave. Interior bluisli- 

 yellow, showing the ornamentation of the outside ; spatula indistinctly 

 marked; margin sharp. Length 7, breadth 5-5, height 2mm. Type. 



Dentition: Hutton, Trans. X. Zeal. Inst., vol. xv, p. 128, pi. xv, 

 fig. N. The Fig. 32 is copied after Hutton. 



Hab. — The type is from Auckland Harbour. My collection supplies 

 the following localities : — North Island : Auckland Harbour, Rakino 

 Island, Cook Strait, Wellington Harbour. South Island : Sumner, 

 Lyttelton, Greymouth. According to Hutton it is found as far south 

 as Dunedin. 



In this instance, again, the late Captain Hutton cannot have seen 

 specimens of A. flammea, Q. & G., or he would never have assigned 

 our small, fragile, and pellucid shell to that species, which is much 

 larger and solicl. This is one of our fairly constant species. Fossil in 

 the Pliocene. Type in the Canterbury Museum, Christchurch. 



