Pleurodon.] I'ELECYPODA. 839 



Distribution. Catalina Islands, Korean Straits, Cape of Good 

 Hope, New Zealand, Australia. 

 Fossil in the Tertiary. 



1. Pleurodon maorianus, Hedley, 1904. Plate 51, figs. 4, 4. 



Pleurodon maorianus, Hedley, Rec. A.M., v, 1904, 87, f. 14 in text ; T.N.Z.I., 

 xxxviii, 72. 



Shell rather large for the genus, inflated, oval, inequilateral, smooth. 

 Beaks small, rounded, submedian, slightly directed forward, approxi- 

 mate. Anterior side short, truncated ; posterior end descending, 

 broadly rounded ; basal margin regularly and narrowly convex. 

 Sculpture none, except a few incremental stria?. Colour white. In- 

 terior white, not nacreous ; margins smooth and sharp. Hinge- 

 plate broad, undulate below, posteriorly produced in a long and broad 

 lateral tooth, having distally a subsidiary tubercle. Cardinal teeth 6, 

 the first of the anterior series slender, the others erect and stout. 

 Ligament minute. Posterior adductor-scar large, the anterior much 

 smaller. Pallial line simple. 



Length, 2-5 mm. ; height, 3-25 mm. ; diameter, 1 mm. (type). 



Type in the Australian Museum, Sydney. 



Hab. Of? Anchor Island, Dusky Sound, in 5 fathoms, type (A. 

 Hamilton) ; Dusky Sound, 30 fathoms (R. Henry) ; off Great Barrier 

 Island, in 110 fathoms ; off Cuvier Island, in 37 fathoms ; Queen 

 Charlotte Sound, in 16 fathoms ; Port Pegasus, Stewart Island, in 

 18 fathoms (Captain Bollons). 



Genus 4. POROLEDA, Tate, 1894. 



Poroleda, Tate, Journ. Roy. Soc., N. 8. Wales, xxvii 1893 (1894), 186. 

 Type : P. lanceolata, Tate = P. Tatei, Hedley. 



Shell like Leda, having an oblique internal cartilage-pit and a 

 small pallial sinus ; the hinge-line (nearly straight) with a series of 

 longitudinal imbricating teeth on each side. (Tate.) 



Distribution. New Zealand, Australia, and Tasmania. 



Fossil in the Eocene of Australia and Pliocene of New Zealand. 



1. Poroleda lanceolata, Hutton, 1885. Plate 51, figs. 5, 5a. 



Scaphula (?) lanceolata, Hutt., T.N.Z.I., xvii, 1884 (1885), 332; Plioc. M., 

 86, 1893; not of Tate, 1894: Hedley, T.N.Z.I., xxxviii, 1905 (1906), 

 71, pi. 2, f. 7. 



Shell small, thin, compressed, smooth, much elongated, not cari- 

 nated behind, equivalve, very inequilateral, the anterior portion 

 short ; valves gaping posteriorly. Beaks situate at the anterior 

 fourth, minute, approximate. Anterior end short, narrowly rounded ; 



