])IPI,0DON I 29 1 



pressed; laterals elevated, lamellar; muscle scars shallow; na- 

 cre bluish, a little thicker in front. 



Length 60, height 36, diam. 14 mm. 



Length 83, height 49. diam. 21 mm. 



New Zealand. 

 Unio menziezi Gray, In Dieffenbach's N. Z., IT, 1843, p. 257. 



— ? MusGRAVE, Phot. Conch., 1863, P^- ^^- ^S- ^■ 

 Diplodon mefiziezi Simpson, Syn., 1900, p. 889. 

 Unio mcnciesionus Reevk, Conch. Icon., XYL 1B65, pl- xxix, 



ftg- 152- 

 Margaron (Unio) mciizieni Lka, Syn., 1870, p. 46. 



An exceedingly variable species, some of the mutations of 

 w'hich are probably worthy of varietal names. Quite a num- 

 ber of the specimens before me are diseased and as a result 

 the shells are considerably distorted. Some of the normal 

 shells are almost evenly elliptical ; some are slightly obovate ; 

 still others are more or less rhomboid. 



Yar. ancklandirns (Gray). 



More elongated than the typical form and subrhomboid; 

 umbones radiately wrinkle-ridged. 



Length 73, height 40.5, diam. 20 mm. 

 Unio ancklandica Gray, In Dieffenbach's N. Z., II, 1843, P- 



257- 

 f Unio aiicklandicHs Sowe:rby, Conch. Icon., X\'I, 1866, pi. 



XXX, fig. 156. 

 Margaron (Unio) aucklandicns Lea, Syn., 1870, p. 45. 

 Diplodon mcnziezi (part), Simpson, Syn., 1900, p. 889. 



The above, though quite distinct typically, absolutely blends 

 into the type. 



Yar. rugiihsiis n. n. 



Shell small, more solid and inflated than the type. 



Length 49, height 31, diam. 19 mm. 



Length 53, height 34, diam. 18 mm. 

 Unio nigatiis Mutton, Tr. N. Z. Inst., XYI, 1884, p. 216. 

 Diplodon mensiesi var. rugatns Simpson, Syn., 1900, p. 889. 



