Rev. 0. Fisher — The Coprolite Pits of Cambridgeshire. 65 



tapering very abruptly to the central beak ; greatest width much less 

 than half the length. Surface of the shell smooth, minutely and 

 closely punctate, and marked on the posterior half with a few faint 

 longitudinal stri^. Length, l-60th of an inch. 



CytJierura cristata, nov. sp., Plate II., Figs. 12, 13. — Shell seen 

 laterally approaching closely C simiUs in shape ; greatest height 

 situated in the middle, and exceeding half the length ; anterior 

 extremity rather obliquely rounded, posterior produced in the middle 

 into a broad obtusely rounded beak ; superior margin boldly arched, 

 somewhat flattened in the middle ; inferior slightly sinuated in the 

 middle ; seen from above, elongated, hexagonal, with nearly parallel 

 sides, and equally tapering mucronate extremities ; width barely equal 

 to half the length. Shell-surface perfectly smooth, except on the 

 ventral surface, which is somewhat waved and rugged, bearing 

 within the inferior border a slightly elevated crescentiform ridge, 

 which is extended partly round the posterior margin. Length, 

 l-55th of an inch. 



Cytheropteron complanatum, nov. sp., Plate II., Figs. 3, 4. — 

 Shell seen laterally sub- semicircular, highest in the middle, height 

 equal to nearly two-thirds of the length ; anterior extremity rounded ; 

 posterior produced into a subacute central beak ; superior margin 

 very boldly arched ; inferior, slightly convex, sinuated in front of 

 the middle ; seen from above ovate, acuminate in front, mucronate 

 behind ; twice as long as broad ; greatest width situated near the 

 middle. Surface of the valves covered with closely set, moderately 

 large circular pits, and having an imperfectly defined transverse 

 sulcus near the middle of the ventral margin ; lateral alse obsolete. 

 Length, l-50th of an inch. 



This is one of the more abundant species in the Montreal beds. 

 EXPLANATION OF PLATE II. 

 Fig. 1. Ci/ihere MacGhesneyi, seen from left side . . . ^ 

 „ „ ,, above 



Cytheropteron complanatum, ,, 



1. 



2. 

 3. 



4. 

 5. 

 6. 

 7. 

 8. Cy there Logani, 



Cythere Dawsoni, 



left side 

 above . 

 left side 

 above . 

 below . 

 left side 

 9. „ „ above . 



] 0. Cythere euspidata, right valve .... 



IL ,, ,, seen from above . 



12. Cytherura cristata, „ left side 



13. ,, „ ,, above . 



14. Cytherura granulosa, ,, leftside 



15. „ ,, ,, above . 



)• X 60 



X 40 



X 84 



III. — On Phenomena connected with Denudation, observed in 

 THE so-called Coprolite Pits near Haslingfield, Cam- 

 bridgeshire. 



By the Rev. 0. Fisher, M.A., F.G.S. 



THE upper portion of the sections in these pits usually exhibits 

 from a foot to a foot and a half of soil, which I call, after Mr. 



vol. VIII. NO. LXXX. 6 



