401 
ribbing corresponds with the South Australian shell in the 
vidth of the ribs, but they are almost straight, nearer together, 
the bridging greatly thickened and proportionately shorter. 
e transverse ridges in the two lateral ribs are present 
as mere nodules, irregularly spaced and not as sharp strongly 
elevated ridges as in the two preceeding. is form easil 
takes its place as a subspecies of Reeves' Callistochiton 
antiquus, 
CALLISTOCHITON ANTIQUUS MAYI, n. sp. 
Pl. ‘xlii:, figs. 8 and 9. 
. . The only opportunity I have had of collecting Chitons 
in North-western Tasmania was limited to one afternoon on 
October 11, 1916, when I had an hour or so on the rocks at 
a place called Penguin. Amongst the shells then collected 
was a small Callistochiton quite new to me, which I concluded 
and put aside as being Iredale and May's new Callistochiton 
C. mawlei, which I had not then seen. Since then my friend 
Mr. M i me a specimen of that shell, and I find 
n 
simply granulose, the network origin of the sculpture is quite 
lost. Under a higher power, however, the network sculpture 
, more numerous and closer together. Measurement, 8 mm. 
x 9 mm. I consider this species diverges most from the dom- 
: mant form of all the su species here dealt with. 
: . Remarks.—In the absence of the examination of the Vic- 
: torian Callistochiton fauna, our knowledge of the effect or 
= otherwise thmus (Hedley: Proc. Linn. Soc 
certainly suggestive but inconclusive, until more Victorian 
material is examined. I hardly think any additional word is 
