202 RICHARDSON : THE LOWER OOLITIC ROCKS OF YORKSHIRE. 
discitce hemera {vide Appendix I., footnote, p. 205). As the Lower 
Trigonia- and Buckmani -Gvii^ are also of this hemera, the Millepore- 
Bed, Whitwell and Cave Oolites (in part at least) and Lower 
Trigonia- and Buckmani -Grits of the Cotteswolds come into line. 
The echinoid evidence would seem to link the Millepore Bed 
and its equivalent limestones with the Pea-Grit ; but against this 
must be placed the evidence of the spinose rlwnchonellids of the 
genus Acanthothyris. In the Buckmani -Grit of the Cotteswold 
Hills little acanthothyrids are not at all uncommon, and some 
specimens have been compared with the Acanthothyris crossi of 
the late J. F. Walker from the Lincolnshire Limestone. Such 
forms and another one with a very regular arrangement of its 
spines (like one well-known to workers in the Cotteswold Hills) 
have been noticed, but only rarely in the Millepore Bed. Phillips 
has figured a specimen apparently of this latter type which he 
obtained from the Millepore Oolite of near Cave (" Geology of 
Yorkshire," Part L, Plate IX., Fig. 18, p. 243). 
The deposits of discitce date in Yorkshire and the Cotteswolds 
contain a number of species that are common to the two districts, 
such as Serpula socialis (Goldfuss), S. deplexa Bean, Spiropora 
straminea (Phil.), Acanthothyris sj). nov., GerviUia prcelonga 
Lycett, G. whidbornei Paris, Lima hellula M. and L.. L. duplicata 
Sow., Ctenostreon pectiniforme (Schloth.), Camptonectes lens (Sow.), 
C. cf. aratus (Waagen), Pinna cuneata Phil., Protocardia buckmani 
(M. and L.), Ceromya bajociana d'Orb., Cucullcea elongata Soa\., 
Cypricardia spp., Isocardia cordata J. Buckm., Volsella. ungulata 
(Y. and B.), Trapezium sp., Trigonia spp., Natica sp., etc. 
The Lower Estuarines. — These beds vary in thickness from 
286 feet on the coast at Blea Wyke, to 120 feet in the Howardian 
Hills, 50 feet at Acklam and to only 15 feet in South-east Yorkshire. 
They are more arenaceous than those composing the Middle and 
Upper Estuarines, having in their lower portion massive sand- 
stones ofttimes curiously false-bedded and extremely irregular, 
and contain (at Blea Wyke at about two-fifths of the distance 
down below the Millepore-Bed) an important marine band called 
the " Eller-Beck Bed." 
The Eller-Beck Bed consists of sandstone in the upper portion 
and shale with associated beds of ironstone in the lower. In the 
Howardian Hills this sandy upper portion passes into a Hydraulic 
