Palaeontologie. 69 



carbon, hydrogen etc. in the course of thc formation of coal from 

 vegetable masses, and the alterations due to dynamic forees. A 

 number of analyses and tables of comparative compositions are 

 given. In the summary the variations in coal are said to be due to 

 1) Original composition — the softer varieties of Vegetation 

 having an initial higher hydrogen percentage. 



2) Duration and character of decay — the initial loss of 

 carbon dioxide may be prolonged by fermentation , thereby raising 

 the hydrogen to the critical point at which it forms an unstable 

 hydrocarbon Compound. 3. Pressure — which restrains the loss of 

 carbon and promotes the formation of water and carbonic acid. 

 Heat causes the formation of hydrocarbons and raises the percen- 

 tage of ash by the great loss of volatile material. 



As a result of his study of the various processes the author con- 

 cludes that the general assumption that the carbon percentage shows 

 the amount of alteration, may not always be true. 



M. C. Stopes (London). 



Johnson, T., A seed-bearing Irish Pteridosperm, Crosso- 

 theca Höninghausij K i d s t o n (Lyginodendron oldhamium, W i 1 - 

 liamson). (Sei. Proc. Roy. Dublin Soc. XIII. 1. p. 1 — 11. pl. I — III. 



1911.) 



The author gives a resume in live or six pages of what is known 

 of the group of Pteridospermae ; he then points out that this group 

 flourished in Ireland; and in four pages gives an aecount of a 

 speeimen from the Coal Measures of Tipperary in which "judging 

 from the carbonaeeous impression, a seed is present still 

 attached to the parent plant, and seated in the midst of the radia- 

 ting cupular lobes." 



The sketch of the speeimen presents some rather curious features. 



M. C. Stopes (London). 



Kubart, B„ Corda's Sphaerosiderite aus dem Steinkoh- 

 lenbecken Radnitz— ßraz in Böhmen nebst Bemer- 

 kungen über Chorionopteris gleichenioides C o r d a. (Anz. kais. Ak. 

 Wiss. Wien, math.-nat. Klasse. N u . XIX. p. 430—431. 1911.) 



Corda fand in den „Sphaerosideriten" des limnischen Kohlen- 

 beckens zu Radnitz— Braz sehr gute petrifizierte Pflanzenreste. 

 Verf. vergleicht diese Sphaerosiderite mit den Kieselknollen aus 

 mesozoischen marinen Ablagerungen der Insel Hokkaido, welche 

 auch schönes Pflanzenmaterial führen. Die Vergleichung ist mö- 

 glich, da die Corda' sehen Knollen zu 88°/ Si0 2 besitzen. Die me- 

 sozoischen Knollen und die botanisch gleichwertigen Torfdolomite 

 des Carbons sind aus marinen Ablagerungen, Corda's Knollen 

 aber aus einem limnischen Kohlenfelde Chorionopteris gleichenioides 

 Cda ist nach den Originalexemplaren ein Farnsorus, zu der Rha- 

 chis Calopteris dubia Cda gehört. Matouschek (Wien). 



Thomas, H. H., On the LeavesofCalamites (Calamocladus 

 Sectio n). (Phil. Trans. Roy. Soc. London, ser. B. CCII. p. 51 — 92. 

 pls. III— V. 1911.) 



A detailed study of the petrified leaves of Calamites with a 

 view to ascertaining the ecological conditions under which the 

 plants grew, as well as the indications of phylogeny yielded by 



