86 JOURNAL AND PROCEEDINGS. 
ones parallel with the hinge as in Cucullza.” Leda, of the Leda 
clay, belongs to this family group. Nucula, another member of the 
family group, was also represented in Paleozoic times. 
TRIGONIA. 
In Australia the sole survivor of its race, Zvigonia Feclinata, a 
beautiful nacreous shell (interior purple or gold) may be obtained in 
Sydney Harbour. Woodward figures Trigonia Costata from the 
British Oolites, giving the general range of the Genera from the trias 
to the chalk, remarking, ‘ not known in Tertiarus.’ Silicified casts 
of Trigonia are found at Tisbury, preserving even the animal itself 
with the gills complete. It is said there are three species, but they 
are probably varieties only. Ina paper I received from the late hs 
Beete Jukes, I find the following: ‘‘ When acting as Naturalist in 
H. M. S. Fly, 1845, I came upon nests of Brachiopods under rocks 
(Waldheimia Australia). They varied so much in size, shape, etc, 
that McLeay proposed to make three species out of my first find. As 
they occured in family groups—parents and children, uncles, aunts 
and cousins—I doubted the specific distinction. After collecting 
some hundreds, it was plainly perceptable that variation in size and 
in external marking from smooth to deep ribbing graduated into 
each other, and there was no definite distinction.” 
I think there must be some mistake regarding the first appear- 
ance of the fossil Z7igonia. Lirodes ma fost striata is mentroned 
by Dr. Spencer as accuring at Burlington Heights in Cambro-Silur- 
ian pebbles. I gave him one of three specimens obtained there, 
and unless we exclude external appearance altogether, it surely must 
be considered a member of the Trigonidz. 
THE CYPRINIDA. 
Representing a genera of shells formerly numerous—are also 
on the wane. The modern Heart Cockle, Zsocaradia Cor., British 
Seas and Astarte Sulcata are examples. Megaladons ‘‘ Megalomus 
Canadensis, Hale,” are said to belong to this group. 
ARICULID. 
The Ariculide or Wing-Shells, to which the famous pearl — 
oysters of Ceylon belong, and perhaps the Prima also (although I 
may add Tryon and other Conchologists consider this latter is 
