MIDDLE CHALK—MICROSCOPIC STRUCTURE. 517 
-- 
Mupe Bay. 
Dover, Kent. 
Hitchin, 
Herts. 
Hunstanton, 
Norfolk. 
Hessle, 
Yorks. 
Rhizammina indivisa, Brady 
X 
Ammodiscus incertus, d'Orb. sp. - 
— 
X 
X 
X 
X 
,, tenuis, Brady 
- 
— 
— 
X 
- — 
,, gordialis, J. & P. sp. 
- 
— 
— 
— 
X 
Tritaxia tricarinata, Reuss - 
— 
— 
X 
— 
— 
Gaudryina filiformis, Berth. 
— 
— 
— 
X 
— 
„ rugosa, d'Orb. - 
— 
X 
— 
— 
— 
Textularia turris, d'Orb. - 
— 
X 
X 
— 
— 
,, agglutinans, d'Orb. 
— 
X 
X 
— 
— 
Bulimina brevis, d'Orb. - 
X 
X 
X 
— 
— 
,, Presli, Reuss- - 
— 
— 
X 
— 
,, elongata, d'Orb.- 
— 
X 
X 
— 
— 
,, Orbignyi, Reuss - 
— 
X 
— 
— 
— 
,, affinis, d'Orb. - 
— 
X 
— 
— 
— 
,, murchisoniana, d'Orb. - 
— 
X 
— 
— 
— 
Bolivina textilarioides, Reuss 
X 
— 
— 
— 
— 
Marginulina sp. ----- - 
— 
— 
X 
— 
— 
Vaginulina recta, Reuss - - - - 
— 
X 
— 
— 
— 
Cristellaria cultrata, Montf. sp. - 
— 
— 
X 
— 
— 
,, gaultina, Berth. 
— 
X 
— 
— 
— 
,, Bronni, Roemer sp. - 
— 
X 
- 
- 
— 
„ convergens, Born. - 
- 
X 
— 
- 
— 
Globigerina cretacea, d'Orb. 
- 
X 
X 
' 
- 
,, marginata, Reuss sp. - 
— 
X 
X 
- 
,, sequilateralis, Brady - 
- 
X 
- 
- 
— 
Anomalina ammonoides, Reuss sp. 
— 
X 
X 
— 
— 
Pulvinulina sp. - 
— 
X 
— 
— 1 
— 
Rotalia Soldan, d'Orb. var. nitida, Reuss - 
X 
X 
1 
The Glohigerince are particularly fine specimens, larger than at 
any other horizon in the chalk. Both G. cretacea and G. marginata 
are, perhaps, the commonest forms which occur. 
With the exception of Bulimina elongata, and Globigerina 
(Ec/uilateralis all these species have been recorded from the Lower 
Chalk. 
Examination of Residues. 
Nine specimens of this zone were treated with the acid solution, 
including five by Dr. Hume. 
The largest percentage of residue occurs in a specimen from 
the higher part of the zone at Dover, 3'68 per cent., while one 
from Beer Cliff, Devonshire, closely approaches this with 3*136 
per cent., the specimens from Culver Cliff (Isle of Wight) and Luton, 
Bedfordshire, come next with 2*24 per cent, and 2*56 per cent, 
respectively. The purest chalk again occurs in the east and north- 
4219. t,l 2 
