400 



DR. W. T. CALMAN ON 



X. austi^alis, sp. n. (text-figs. 6, 7, & 8). Dorsal outline form- 

 ing a distinct angle or concavity at the base of the auricle, which 

 is not more than half the total depth of the valves and descends 

 on the hind margin for not more than half the distance from the 

 anterior notch to the ventral edge. The lines of growth on the 

 auricle are much more closely set and less prominent, and are not 

 at all conspicuous on the inner surface. The anterior border of 

 the auricle on the inside overlaps as a broader band which is 



Text-figure 7. 



y 



Xylotrya australis, sp, n. Syntype from Auckland. 



A. External surface of pallet. B. Single segment of 

 the pallet, further enlarged. 



generally slightly raised from the inner surface. Jhe pallets 

 (text -fig. 7) have the segments thin and fragile and more widely 

 spaced, the average interval being estimated at about one-third 

 of the width. The distal margins of the segments are concave 

 or obtusely V-shaped, with a delicate membranous border, at the 

 base of which the calcified portion shows a series of coarse and 

 somewhat irregular serrations which become very conspicuous in 

 dried specimens. The stalk is smooth and shorter than threo 



