THE CONCHOLOGIST. 



43 



Sphaerium rivicola, Leach. 

 An abundant and well-distributed form. 



Sphaerium ovale, Fer. 

 Scarce and local. In the autumn of 1889 

 I collected three .specimens in a ditch in a 

 field near to Eroughton Castle. They were 

 small specimens, but undoubtedly S. ovale. 

 The Rev. S. Spencer Pearce records a single 

 specimen, dead, in good condition, valves 

 united, from the canal near Wolvercot. 



Sphaerium lacustre, Mi-ill. 

 Though never occurring in any abundance, 

 it is well distributed over the county. 



PLSIDIUM, C. Pfeiffer. 



Pisidium amnicum, Midi. 

 This, the largest of our Pisidia, ocurs 

 througliout the county in great abundance. 



Pisidium fontinale, Drap. 



P\airly common. 



I. Banbury. — Abundant in River Cherwell. 



3. AV'ychwood and Charlbury. — Common. 



5. Bicester. — Weston-on-the-Green, Rev. A. 



Matthews (Norman, 1857). 



6. Oxford. — Common. 



Var. pulchellum, Jenyns. 



5. Bicester. — ^Weston-on-the-Green, Rev. A. 



Matthews (Norman, 1857). 



6. Oxford. — Common, numerous records. 



Var. henslowanum, Shep. 



I. Banbury. — Two or three from the Moat 

 at Broughton Castle (Stretch, 1S55). 



6. Oxford. — Recorded by Whiteaves in 

 1857 as abundant; occurs in the 

 district, but is much rarer now. 



Pisidium pusillum, (hnelin. 

 Common, and well distributed. 



Var. obtusale, Lam. 



6. Oxford. — Stream near Botley (Whiteaves, 

 1857), (Dalton, 1855). 



Pisidium nitidum, Jenyns. 

 Not at all common, and very sparingly 

 met with. 



I. Banbury. — Hanwell (Stretch, 1855), 

 near Banbury, three specimens, 1887. 



6. Oxford. — Very rare (Whiteaves, 1857), 

 rare (S. Spencer Pearce, 1883). 



Pisidium roseum, Scholtz. 

 I have had a number of specimens sub- 

 mitted to me named P. roseu??i, but all 

 have, on careful examination, proved to be 

 P. nitidiiin. As yet, there is no satisfactory 

 record of this species having occurred in 

 Oxfordshire. 



UN I ON IDA-:. 

 UNIO, Philippson. 



Unio tumidus, Phil. 



Fairly common in the Rivers Cherwell 

 and Isis, and the Oxford and Birmingham 

 Canal. " In 1854," says Mr. Whiteaves, 

 " there was a great mortality of this (?) 

 species, occasioned by drought, and by rats 

 devouring them ; the banks of the Cherwell 

 were lined with their shells." Mr. Whiteaves 

 seems, however, to have confused the present 

 species with pictontin, and all his notices 

 under iumidus apply with ecjual force to the 

 species pictorum., which is the commoner of 

 the two forms. Unio pictorum is not men- 

 tioned in the list, though it appears in 

 the collection in the University Museum 

 (S. Spencer Pearce). 



Unio pictorum, L. 



Plentiful in same localities as the pre- 

 ceding species, as are also the varieties 

 radiatiis, Moq., and rostratus, Brown. 



