328 PLAXIPHORA. 



each side closely concentrically sulculate. Anterior valve having 

 about 7 or 8 ribs, sometimes with some intercalated subobsolete 

 riblets. Posterior valve small, the mucro subposterior, swollen. 



Interior blue. Anterior valve having 7-8, median valves 1 slit; 

 teeth long, acute, scarcely thickened at edges of the slits. Posterior 

 valve having an obtuse insertion plate, a little sinuated in the middle 

 behind. Sinus broad, straight, spongy. 



Girdle wide, thin, hardly sinuated behind, tessellated with brown 

 and ashy, beset all over with sparse, delicate, short setae, longer at 

 Ihe sutures. 



Length 70, breadth 39 mill.; divergence about 110. 



Australia? (Haines Coll., and Coll. McGill University, Mon- 

 treal.) . 



Euplaciphora excurvata CPR., MS. 



This shell has a general external resemblance in size and shape to 

 P. cuprea, from which it is known at once by the color and sculpture 

 outside, by having no posterior slit in the girdle, and inside by the 

 smoothness and sharpness of the insertion-plates. It also resembles 

 P. superba, but is entirely destitute of sutural pores. 



P. CJKLATA Reeve. PI. 58, figs. 21, 22. 



Shell oblong-ovate, somewhat attenuated anteriorly, terminal 

 valves (the posterior of which is small and slanting) and lateral 

 areas of the rest broad-ribbed and neatly carved with close-set waved 

 lamina? ; central areas very minutely reticulated. Beautifully orna- 

 mented with green and pink. Ligament horny, here and there 

 bristly. (Reeve.) 



New Zealand (Earl, Cuming.) 



Chiton ccelatu* Rv., Conch. Icon., t. 17, f. 101 (1847). Strepto- 

 chiton cupreiis CPR., MS., olim. ? Tonicia zigzag HUTTON, Trans. 

 N. Z. Inst. iv, p. 181 (1872.) 



The verdigris green and peculiar pink color-pattern is character- 

 istic and singularly beautiful. 



Von Martens has stated that Tonicia zigzag Hutton is a synonym of 

 " Acanthopleura " ccelata Rv. (Crit. Cat., p. 49) ; a conclusion 

 accepted by Hutton (Man. N. Z. Moll., p. 115, 1880). As in other 

 cases of alleged identity, the original type of zigzag should be 

 re-examined. Button's description is as follows : 



Tonicia zigzag Hutton. Oblong; mantle slightly tomentose; 

 valves slightly flattened on each side, but not keeled; posterior 



