JACKSON : ON FOSSIL PEAEL-GEOWTHS. 319 



Geological age. — Cretaceous (Senonian). Pound in the Crag 

 deposits as probably derivative fossils from the Chalk. 

 Locality. — Near Orford Castle, Suffolk. 

 Collection. — Manchester Museum (E.. Cairns Coll.) [L. 1550]. 



Family OSTREID^. 

 OsTKEA EDULis, LinuBeus. PI. XIV, Fig. E. 



Attached to a valve of this species amongst a collection of Coralline 

 Crag fossils in the Manchester Museum is an almost spherical pearl 

 (see above plate). Like the shell itself, the pearl, which is about 

 4 mm. in diameter, has lost a good deal of its beautiful nacreous nature, 

 and appears almost porcellanous. Beyond the fact that it was originally 

 in the old Manchester Museum and came from Kamsholt, no particular 

 history is attached to it. 



Geological age. — Pliocene (Coralline Crag). 



Locality. — Eamsholt, Suffolk. 



Collection. — Manchester Museum [L. 4696]. 



OsTKEA TENEEA, J. Sowerby. 



Ostrea te^iera, J. Sowerby: Min. Conch., 1819, vol. iii, p. 95, pi. cclii' 

 figs. 2, 3. 



Whilst cleaning up and working out the material from between the 

 valves of a specimen of the above species in the Caroline Birley 

 Collection, I came across a small spherical body, not quite 2 mm. in 

 diameter, bearing a strong resemblance to a pearl. It is dirty brown 

 in colour, but exhibits the characteristic nacreous lustre. 



Geological age. — Lower Eocene (Woolwich Beds). 



Locality. — Croydon Gasworks. 



Collection. — Manchester Museum (Caroline Birley Coll.) [L. 8703]. 



GrRTPH^A DiLATATA, J. Sowerby. 



Gryphma dilatata, J. Sowerby: Min. Conch., 1816, vol. ii, p. 113, 

 pi. cxlix. 



Attached to the upper valve of a specimen of the above species 

 are three small pearl-growths, close together, and situated very near 

 the hinge. They are dark-coloured, and partake of the same nature 

 as the shell itself. 



Geological age. — Jurassic (Oxford Clay). 



Locality. — Cowley, Oxford. 



Collection. — Manchester Museum (Manning Coll.) [L. 6360]. 



Family LIMID^. 



Lima scabka, Born. 



Lima scahra, Born: Index Mus. Caesar. Vindobon., 1778, p. 110. 



Amongst a' small collection of Tertiary fossils collected by Sir 

 William Rawson in the Bahamas are two odd valves of this species, 

 and in the interior of one of these are a number of attached pearl- 

 growths. The shell is thick and coarsely grown, slightly deformed, 



