116 Mr. H. Seeley on Cambridge Palaontology : — 



has assigned it as a synonym); and the discovery of this species 

 in Great Britain adds to the probability that it was previously 

 taken in Hampshire. It is worthy of notice, moreover, that 

 Montagu was well aware that Bulla rivalis was a common West 

 Indian shell, and that, knowing this, he did not call in question 

 the discovery of Mr. James Hay. 



The shell brought by Mr. Sowerby from Anglesea, and erro- 

 neously named by him Physa acuta, has nothing to do with the 

 present species, but is merely a produced form of P. fontinalis. 



The recent addition to our lists of two freshwater Mollusca, 

 SphcErium pallidum (Gray) and Physa acuta (Drap.), and the re- 

 discovery in some abundance of Vertigo alpestris (Alder) in the 

 Lake district — a shell of which only one British specimen was 

 previously known, and the specific value of which had con- 

 sequently been called in question — shows that the conchologist 

 need not despair of novelties even in that well-worked branch of 

 his hobby, land and freshwater shells. 



My mentioning that I am indebted to the pencil of my kind 

 friend Mr. Alder for the figures that illustrate this paper will at 

 once assure zoologists that they are all that could be desired as 

 regards correctness. 



EXPLANATION OF PLATE IX. figs. 5-9. 

 Figs. 5 & 6. Physa acuta (Draparnaud), variety, front and back view of 



shell. 

 Fig. 7- The animal of the same, viewed from below ; the digitations of the 



mantle are represented at their fullest expansion. 

 Fig. 8. Outline of head, viewed from above. 

 Fig. 9. Two denticles of the lingual membrane. 

 Sedgefield, co. Durham, Jan. 1, 1861. 



XVII. — Notes on Cambridge Palaontology"^. By Harry Seeley. 

 [Plates V. & VI.] 

 I. Some new Upper Greensand Bivalves. 

 The following list is far from including all our local species : 

 of several the fragments of casts yet obtained are not sufficient 

 for description ; these, with others not in Cambridge, would 

 probably outnumber those enumerated. 



It is with pleasure I acknowledge much kind assistance in 

 forming the list, such as it is. Mr. Carter has allowed me con- 

 stant access to, and the loan of specimens from, his rich collec- 

 tion ; Mr. Farren, the careful collector and dealer, placed the con- 



* In these notes it is intended to describe such new forms as have been 

 met with in the country round Cambridge. They will include the forma- 

 tions from Middle Oxford Clay to Upper Chalk, and form an appendix to 

 an intended memoir (o illustrate Mr. Barrett's geological map. 



