504 Dr. Nils Olof Hoist — The Ice Age in England. 



clearly shown in one of the perfect zooecia but is hardly visible in the 

 other. What may be the remains of a fourth bud occurs on the right- 

 hand side of the zocecium of the main branch (cf. Vine's figure of his 

 type-specimen, Proc. Yorks. Geol. Poly. Soc, new series, Vol. xii, PI. vi, 

 fig. 15). x about 27 diameters. British Museum specimen No. D. 2062. 

 Albian, Gault. Cambridge. T. Jesson Collection. 



3. Rhammatopora pembrokics. Three zooecia of the type-specimen, in one 



of which the intra-terminal front wall has collapsed along the line of the 

 rhamma. The rhamma is not clearly shown in the other two zooecia. 

 x about 29 diameters. Part of British Museum specimen No. D. 22987. 

 Cenomanian, Chalk Marl. Cambridge. F. Mockler Collection. 



4. Rhammatopora pembrokics. A single zocecium of another specimen 



showing the rhamma. x about 26 diameters. British Museum specimen 

 No. D. 22986. Cenomanian, Chalk Marl. Cambridge. F. Mockler 

 Collection. 



5. Charixa vennensis. Several zooecia of the type-specimen showing the 



method of branching and in one place an example of rejuvenescence. 

 X about 29 diameters. British Museum specimen No. D. 22950. 

 Albian, Upper Gault, Cowstone horizon. Black Ven, Charmouth, 

 Dorset. Collected by W. D. Lang. 



6. Charixa vennensis. A renewed zocecium of another specimen, showing the 



rhamma. x about 35 diameters. British Museum specimen No. D. 

 22935. Albian, Upper Gault, Cowstone horizon. Black Ven, Charmouth, 

 Dorset. Collected by W. D. Lang. 



7. Mystriopora mockleri. Several zooecia of the type-specimen showing the 



early uniserial stage with bilateral branching passing into a pauciserial 

 stage with unilateral branching. X about 26 diameters. British 

 Museum specimen No. D. 21670. Cenomanian, Chalk Marl. Cambridge. 

 F. Mockler Collection. 



8. Distelopora bipilata. Several zooecia of the type-specimen showing the 



early uniserial stage with bilateral branching passing into a multiserial 

 condition with unilateral branching. X about 28 diameters. British 

 Museum specimen No. D. 23019. Cenomanian, Chalk Marl. Cambridge. 

 F. Mockler Collection. 



9. Distelopora bipilata. A single zocecium of another specimen, more adult 



than those of fig. 8, showing very clearly the number and nature of the 

 spines and the very wide intra-terminal front wall, x about 30 diameters. 

 British Museum specimen No. D. 21883. Cenomanian, Chalk Marl, 

 Cambridge. F. Mockler Collection. 



IY. — The Ice Age in England. 



By Dr. Nils Olof Holst (late of the Geological Survey of Sweden). 



(Concluded from the October Number, p. 444.) 



IN the preceding paragraphs it has been shown that, after the inland 

 ice had attained its southernmost limit and had spent its force, 

 there commenced in Southern England the last of many stages of land 

 depression. This carried with it a complete reversal : the temperature 

 was raised, the periphery of the inland ice melted, its pressure was 

 lessened, and a rapid .rise of the land — the Mousterian elevation — 

 introduced a great rise, to which the origin of the submerged forests 

 bears witness. Nevertheless, the greatest part of the land depression 

 persisted even after Mousterian time, and this explains the continuance 

 of the melting and its increased rapidity, as well as the rapid 

 northward withdrawal of the inland ice, which we shall soon 

 consider. 



