UNIO. 147 
Cisse ACEPHALA: 
SUB-CLASS._-PELECYPODA. 
Order.—-LAMELLIBRANCHIATA. 
S2b-order.—ISOMVA. ‘ 
Family.— UNIONID&. 
Genus.—Unt0 Philippsson. 
Elongated, solid ; /atesa/ teeth strong ; Zele distinct. 
I. U. TUMIDUS (swollen) Philippsson. Pl. IX., f. to. 
Ovate, very solid, dark brown; efedermzs smooth. L. 1°5 inches. 
B. 3 inches. 
Common in many rivers, ponds and canals in England 
and Wales, but not found in Scotland or Ireland. 
Jeffreys gives the average length and breadth of this 
shell as 1°5 in. and 3 in. respectively, but much larger 
measurements are not uncommon. Mr. G. S. Tye (Sc. 
Gossip, April, 1885,) gives the length of one in his 
possession as 2°25 in. and the breadth 5 in. This and 
other large specimens were taken “in a pool near Bir- 
mingham.” I have taken specimens in Copmere, Stafford- 
shire, of equal length and over 4 inches in breadth, but 
Jeffreys’ measurements are correct for the average size. 
Var. I. miilleri (Rossm.). More oval in shape. 
Var. IL. ovdlis (Mont.). Wedge shaped, dark coloured. 
Var. Il. fouderosa (Pasc.). Warger, very solid, dark 
coloured. 
