Cossmann and Peyrot (Conch. Neogen. l'Aquitane, Tome 1, pt. 3, p. 543, 1912) have decided to adopt Gray's family name for the Lasaeas, and this has been followed by Odhner (1924, p. 78).
Lasaea Brown, 1827; Ill. Conch. Gt. Britain, Explan. pl. 20, f. 18.
Lasaea hinemoa n. sp. (Figs. 27, 28).
Shell close to L. australis (Lamk.), but smaller. Darker coloured, entirely dark reddish or reddish-brown instead of largely whitish. A little less elongate and more regularly quadrilaterally oval, the dorsal margina forming an almost straight line under the beaks; in australis the posterior dorsal margin slopes suddenly down at the
umbo to meet anterior dorsal margin. Australis also has a tendency, not shown in hinemoa to become subtriangulate, and develop an anterior bluntly angled rostrum; this is more prominent still in scalaris Phil. Hinemoa has no sculpture beyond very fine concentric rugae; australis has in addition minute irregular radial scratches.
Length, 3.7 mm.; height, 2.9. mm. (the type is a large example; most shells are not much more than half this size).
Locality: Riverton, Southland, on seaweeds (type); a common Forsterian shell, but not reported north of Banks Peninsula. Chatham Is., several valves.
This is the “Lasaea miliaris” of Suter, not of Philippi. Suter's description is not very useful, and his figure is wretched.
Lasaea rossiana n. sp.
This is proposed for the Macquarie Island shell figured by Hedley in the Mollusca Austral. Antarctic Exped., p. 33, Pl. 4, Figs. 42-44, 1916, and identified by him as L. consanguinea Smith. Ker-guelan topotypes of that species, however, though closely similar in shape and general appearance are rather more elongate and distinctly more inequilateral, with less prominent beaks. Consanguinea has the appearance of a strong slope to the anterior end, as if it had been pulled from that direction. Moreover, the hinge of rossiana, well figured by Hedley, is altogether more massive and disproportionate to the size of the shell than that of consanguinea, which is much more like australis in this respect. Both rossiana and consan-guinea have only fine concentric rugae for sculpture.
I have this species also from the Auckland Is., where it is rather common as a beach shell, and is probably what Suter recorded from there as miliaris.
Odhner's records of “Lasaea minutissima” (1924, p. 78) refer to a mixture of several species. Probably he had no true minutissima at all, his Stewart Is. shells will be L. hinemoa, and his subantarctic specimens mostly rossiana.
This species is not itself found at the Chathams, but I have named it here in order to describe by comparison a very similar form which does occur there.
Lasaea rossiana vexata n. subsp. (Figs. 41, 42).
Extremely close to the preceding, and at first sight identical. The posterior dorsal margin, however, as in L. australis drops down under the umbo to meet the anterior dorsal margin; in rossiana the line of the margin is more continuous. Translucent white, the hinge reddish; rossiana is brownish or red. Differs constantly in having fine wrinkles and punctures besides the concentric striae. It is practically on this last feature that I give the Chatham shells a distinct name; all the valves from there show it, while I have not been able to see it on any of a large series of rossiana. The shells are distinct from L. neozelanica Suter (which also has wrinkles) and are evidently the same as those Suter identified as L. scalaris Phil. (Suter, 1913, p. 928) from Taumaki and Stewart Islands—the latter species is a totally distinct form and does not occur in New Zealand.
Length, 2.4 mm.; height, 1.9 mm.
7 valves from the Chathams.