836 PELECYPODA. \Protobrancliia. 



Smith, I.8.O., kindly sent me the following report : ' These valves 

 are very like but not quite the same. They are more inequilateral 

 that is, the posterior half is rather longer in proportion to the anterior 

 the transverse sculpture is finer, and the posterior escutcheon decidedly 

 broader.'" These rather slight differences may be due to influences of 

 the quality of the bottom, depth, &c. 

 Fossil in the Pliocene. 



2. Leda fastidiosa, A. Adams, 1856. Plate 54, figs. 18, a. 



Leda fastidiosa, A. Ad., P.Z.S., 1856, 49 ; Hanley, Thes. Conch., iii, 12.3, 

 pi. 228, f. 82, 83 ; Grit. List, 49 ; Mutton, J. de Conch., 1878, 54 ; 

 M.N.Z.M., 165 ; Hedley, T.N.Z.I., xxxviii, 1905 (1906), 70, pi. 1, f. 1, 2 ; 

 Clarke, T.X.Z.L, xxxvii, 416, pi. 32, f. 3. ? L. semiteres, Hutton, T.N.Z.I., 

 ix, 1876 (1877), 598. 



Shell transversely ovate, rather thin, shining, yellowish, from 

 nearly smooth to strongly concentrically sulcate, with a sharp pos- 

 terior rostrum. Beaks situate near the anterior third, approximate, 

 directed backwards, pointed. Anterior side rounded, somewhat pro- 

 duced ; posterior end angulated, with a sharp beak, the dorsal margin 

 concave ; basal margin broadly rounded. Lunule indistinct. Escut- 

 cheon prominent, lanceolate, bordered by ridges which are smooth and 

 rounded anteriorly, the dorsal margins of the valves forming a sharp 

 median keel. Sculpture varying from the least trace of concentric 

 riblets to a considerable development, but they are always present at 

 the posterior angle of the escutcheon ; a microscopic punctate pattern 

 is a constant feature, present also on the finely striate escutcheon. 

 Epidermis thin, shining, sometimes a little iridescent. Colour yellowish, 

 lighter at the umbones. Interior white, lightly iridescent ; margins 

 smooth. Hinge angulate ; resilium small, triangular ; teeth V-shaped, 

 the slightly shorter anterior series with about 12 teeth, the posterior 

 with about 14 ; near the beaks the teeth are minute. Adductor-scars 

 not deep, the posterior scar slightly larger than the anterior. Pallia! 

 line simple. 



Length, 8-5 mm. ; height, 5 mm. ; diameter, 4 mm. 



Type in the British Museum. 



Hob. --New Zealand (Cuming). Off Great Barrier Island, in 

 110 fathoms. 



.Fossil in the Miocene and Pliocene. The specimens should be 

 re-examined. 



Genus 2. MALLETIA, Desmoulins, 1832. 



Malletia, Desm., Actes Soc. Linn. Bordeaux, v, Feb. 1832, 85. Type : 

 ,17. chilensis, Desm. Solenella, Sowerby, Dec. 1832. Ctenoconcha, Gray, 

 1840. Neilo, A. Adams, 1854. 



Animal having the margins of the mantle fringed and with ventral 

 lobes ; siphons close together, long and slender, completely retrac- 

 tile ; labial palps with appendicles, rolled up and as long as the shell ; 



