8 
found in the Dogger beds occur often as casts, or with their 
shells so badly preserved that it is difficult to determine whether 
more than one species is present, so they are referred to 
Terebrcitula trilinecita , a species which was founded by Young 
and Bird, on internal casts. Another peculiarity of the 
distribution of this group in Yorkshire is the number of species 
which occur in the Lower Calcareous grit and Passage beds. 
The following Yorkshire species are very rare: Terebrcitula 
Bentley i, Dav., Walclheimia bucculenta, Sow., Waldheimia 
impressa , v. Buch., Rhynchonella Icicunosa , Schlot., Rhynchonella 
inconstcms, Sow. Among the species which are rather scarce are 
Terebrcitula bullcita , Sow., Terebrcitula Fileyensis , Walk., Tere- 
bratula insignis , var., Maltonensis , Oppel., Terebrcitula intermedia , 
Sow., Rhynchonella spinosa , Sow. The following species are 
very abundant, viz., Lingula Becinii , Phil., Discinci reflexci , Sow., 
Terebrcitula trilinecita , Y. and B., Waldheimia Hudlestoni, Walk., 
Waldheimia obovatci , Sow., Rhynchonella Leedsii , Walk., Rhyn¬ 
chonella socialis , Phil., and Rhynchonella Thurmanni, Yoltz. 
The other species are moderately common. 
Lingula Becinii , Phil. This species is very plentiful in the 
grey micaceous sands of Blue Wyke (lower part of B, fig. 3). 
It also occurs in a ferruginous stone at Castle Howard station 
(2. a., fig. 7). 
Discinci reflexci , Sow. It occurs at Blue Wyke along with the 
above species, but scarcely ascends to the top of the Grey Sands. 
Found also in the ferruginous bed at Castle Howard. 
Rhynchonella cynocephala , Rich. Occurs chiefly at Blue Wyke 
in the upper part of the Yellow Sands (C. fig. 3), but usually 
below the Terebrcitula- bed. 
Waldheimia ? sp. n.? Found in blocks of shelly dogger, 
belonging to the Yellow Sands, which have fallen from the 
cliffs; these are in position probably a few feet below the 
Terebrcitula- bed. 
This shell is small, circular or ovate, the smaller valve 
carinated, somewhat resembling Waldheimia Walkeri from the 
Neocomian of Tealby. 
Terebrcitula submaxi Hat a, Dav. Specimens resembling this 
species occur in the Rosedale Ironstone, but their precise 
