CH. XXm] PSARONIUS 413 



ance presented by their polished surfaces is said to have 

 given rise to the appellation Staarsteine (starling stones), a 

 term expressing a resemblance, more or less remote, to a 

 starling's breast. It has been suggested that this word is a 

 corruption of Stern Steine or star stones \ a descriptive term 

 suggested by the stellate arrangement of the vascular strands 

 in transverse sections of the roots. Parkinson 2, in his Organic 

 Remains of a former World, speaks of these stems as starry 

 stones. The history of our knowledge prior to 1854 is sum- 

 marised by Stenzel. At first compared with corals or the 

 stems of sea-lilies, Psaronii were recognised by Sprengel, who 

 first used a lens in the examination of the fossils, as fern stems 

 most nearly allied to those of recent Cyatheaceae. By other 

 authors, e.g. Schlotheim and Sternberg, they were referred to 

 Palms, and by Brongniart considered to be the lower portions 

 of Lycopodiaceous (Lepidodendron) stems. Corda and many 

 subsequent authors selected the Marattiaceae as the most 

 closely allied family among existing plants. 



Psaronius is represented by specimens obtained from the 

 Lower Permian of Saxony and Upper Carboniferous rocks in 

 Central France, also from Bohemia, Brazil and North America. 

 As yet a few fragments only have been found in the English 

 Coal-Measures. The genus was recognised by Williamson' who 

 described the roots and a small piece of the vascular tissue of a 

 stem which he called P. Renaulti, and this type has since been 

 more fully described by Scott*. The roots of another species 

 have been described by Butterworth^ as P. Cromptonensis. 



It was pointed out in the account of Lepidodendron that 

 several generic names have been used for the same type of 

 stem in different states of preservation ; in Psaronius accidents 

 of fossilisation have been responsible for a similar confusion in 

 nomenclature. The name Psaronius is applied to petrified 

 specimens which, as a rule, lack external features. Casts or 

 impressions of Palaeozoic tree-fern stems provided with leaf- 

 scars are described as species of Caulopteris, Megaphyton, and 

 less commonly as Ptychopteris (figs, 297—299). The first name 



1 Stenzel (54) p. 753. ^ Parkinson (11) A. 



3 Williamson (76). ■* Scott (08). " Butterworth (00). 



