ai Shs al eo eek De EL eerie ERR 
DU eee E : xx 
63 
dredged by Mr. Gabriel in 5 fathoms, at Western Port, 
Victoria, measuring 33 x22 mm., in which the ray ribbing 
of anterior valve is well defined, but the closely-packed inter- 
mediate.ribbing is hardly discernible, except near the margin ; 
one of the coarse hairs on this specmen is 9 mm. long. Dr. 
W. G. Torr kindly showed me his Victorian specimens, which 
are similar to mine. 
Tasmanian form.—Both Mr. W. L. May (of Tasmania) 
and Dr. Torr have been good enough to lend me their 
Tasmanian shells for the purposes of this paper. Mr. May 
writes that it is rare at Port Arthur. These Port Arthur 
specimens show a considerable divergence from most of the 
New South Wales shells, and are approached most nearly by 
the dredged specimen, before referred to, from Western Port, 
Victoria. The largest shell from Port Arthur is in Mr. May’s 
collection, and measures 41x31 mm., has practically no 
decussation on dorsal or pleural area, but the smaller shell 
shows it to some extent ; the riblets on the anterior valve are 
not as strong and the tail valve is more elevated than the 
New South Wales type. But the small shell from Sydney, 
before referred to, diverges from the type quite as much in 
these re . I therefore do not feel justified in separating 
the Tasmanian Port Arthur shell from the New South Wales 
and Victorian ones: they all show the coarse, branching hairs 
d” p 
uc. er amoun ) 
terial from the other States I hesitate to quote this 
Character as one of the distinguishing ones of the South 
i hell. 
P 
adult South Australian shell is much larger, often double the 
Size, of its congener. 
