left valve. Sculpture of rather sharp, concentric, irregularly-spaced lamellae, about five per millimetre, with wide, flat interspaces which are occupied by dense vermiculate radial threads. Left hinge with two curved triangular cardinals; margins of lunule and escutcheon raised distally to function as lateral teeth; lunular one with low ridge below, posterior one with trace of a groove. Right hinge with curved triangular cardinal and a strong anterior also a strong posterior lateral, each of which forms with raised margin a deep socket to receive lateral tooth of left valve. Adductor impressions not strongly marked but apparently triangular, anterior one slightly elongated.

Holotype in Dominion Museum.

Height, 5.6 mm.; length, 6.3 mm.; inflation (1 valve), 1.2 mm.

E. staminifera differs from E. papatikiensis in shape, the beaks being considerably higher, so that the angle between dorsal and lunular margins is less. Also the left anterior lateral of E. papatikiensis is well developed and distant from the lunular margin.

When Iredale (1924, p. 206) introduced Notomyrtea for Australian shells with fine radials in the concentric interspaces, he did not discuss Eulopia proposed by Dall. for American shells with the same feature. Recently Finlay (1926, p. 461) transferred Myrtea (Eulopia) papatikiensis Marwick to Notomyrtea, also without discussing Eulopia. The only outstanding difference from the New Zealand shells shown by E. sagrinata is the considerably greater inflation. The general shape, sculpture, and hinge are so alike that it would be well to associate the groups generically. The radial ornament is a very persistent character and marks clearly defined groups of extended range both geographically and stratigraphically; it therefore justifies generic recognition of Eulopia.