THE GIRDLE SCALES OP ISCHNOCHITON. 
slitting are somewhat weak. On account of the peculiar scales 
the subgeneric name of Chartoplax becomes appropriate. 
Figs. 1, 2, and 3 were all drawn to the same scale of magnifi- 
cation from shells 17 mm. in length. In each case a group of 
scales in the mid zone between valve and girdle margin was 
selected. 
In fairness to Iredale and Hull, the writer notes that the 
Disaster Bay shell, although small in size, shows evidence of 
old age. The girdle scales are somewhat rubbed and the fine 
striation obscured, although it is undoubtedly present. 
Plate XVII. 
Fig. 1. Ischnochiton (Chartoplax) pur a Sykes, topotype, dredged by Gatliff and 
Gabriel in 6 to 10 fathoms off Portsea, Port Phillip, Victoria. Girdle 
scales x220. 
Fig. 2. Ischnochiton crispus Reeve, Narooma, N.S.W. Girdle scales X220. 
Fig. 3. Haploplax smaragdina Angas, Narooma, N.S.W. Girdle scales X220. 
[ 166 ] 
