212 Dr. E. A. Newell Arber — Coal-measure Calamites. 



Cf. Pentellina saxoeum (Orbigny). 

 Fig. 16. Internal section, x 10. 

 ,, 26. ,, ,, X 20. 



,, 46. ,, ,, X 10. 



The specimens figured on this Plate are from No. 1 pebble. 



Plate IX. 

 Lacazina wichmanni, Schlumberger. 

 Fig. 1. Longitudinal section, x 12. 

 ,, 2. Transverse ,, x 12. 



,, 3a. Longitudinal section of a compressed example, x 10. 



Cf. Pentellina saxokum (Orbigny). 

 ,, 36. Internal sections, x 10. 



Okthophragmina sp. 

 ,, 4. Horizontal section of a fragmentary disc showing the internal 

 characteristic rectangular chamberlets and annulations of growth. 

 X 8. 

 Specimens represented by Figs. 1-4 are from No. 1 pebble. 



Carpenteria conoidea, Kutten. 

 ,, 5. Longitudinal section of interior exhibiting the early conoidal growth, 

 a widened base, and chambers of crescentic form. From No. 12 

 pebble, x 10. 



Alveolina cf. melo (Fichtel & Moll). 

 ,, 6a. Longitudinal view of interior. X 10. 



Lithothamnium kamosissimum (Eeuss). 

 ,, 66. Parts of branches seen in longitudinal section, x 10. 

 ,, 7. The same, more highly magnified, displaying the rectangular cell 

 structure of the tissue, x 25. 



Specimens represented by Figs. 6a-7 are from No. 2 pebble. 



III. — A Note on Submedullary Casts of Coal-measdre Calamites. 



By E. A. Newell Aeber, M.A., Sc.D., F.G.S. 

 ri^HE pith-casts of Calamites are common Coal-measure fossils, 

 X sometimes of use in helping to fix tlie horizon of certain coals. 

 They are, however, notoriously difficult taxonomically, and in 

 several cases tliere is difference of opinion among authorities both 

 as to the essential characters of a particular type of pith-cast, 

 and also as to what is the most nearly correct name to apply to it. 

 Immense space is still taken up hy arguments as to Avhat, exactly, 

 some ancient and often manifestly rough drawing, supposed to 

 represent a type, really depicts — with a view to maintaining a strict 

 priority as regards nomenclature. If the original specimen is now 

 lost, as is not infrequently the case, the guessing still continues. 

 Some workers are not content to start their synonymies chronologically 

 with the next oldest figure, the original of which still survives and 

 the nature of which is agreed to on all hands. 



But apart from such cases, there are not a few specific names in 

 vogue in regard to Calamite pith -casts, and also some other genera, 

 which are purely indefinahle. 'I'hey are applied to certain fossils 

 because there exists some, usually ancient, figure which they some- 

 what resemble, but if we are asked to define these species in relation 



