72 TRANSACTION'S. NATURAL HISTORY SOCIETY OF GLASGOW. 



From the clear manner in which well-preserved specimens show 

 the rootlet-scar I am inclined to think the rootlet did possess 

 some provision for effecting a separation from the rhizome when 

 its period of usefulness ceased. Possibly their mode of removal 

 was primarily by decay, but when that took place they appear to 

 have been removed in a definite manner, leaving behind them a 

 clearly-defined scar without any remains of a shrivelled rootlet. 



Stigmaria being the most common of all fossil plants was 

 naturally one of the earliest to be observed and described by 

 writers on Paleobotany. As early as 1720 Yolkmann gives a 

 figure of Stigmaria. 1 Xeither was Stigmaria overlooked by Ure, 

 who in his "History of Piutherglen and East Kilbride" 3 gives a 

 rather interesting portion of a rhizome, showing the scar sur- 

 rounded by rhomboidal meshes. On the same Plate, at fig. 7, he 

 further gives a representation of the basal portion of a rootlet. 



Stigmaria is also illustrated by Parkinson 3 and Martin, 4 who, 

 under the name of Phytolithus plantites, publishes three plates of 

 this fossil. The specimen given on PI. XII. represents a very 

 interesting state of preservation. Here, owing to the manner in 

 which the stone has been fractured, the fossil has been so split 

 that it exhibits the cast of the pith-cavity on which is impressed 

 the openings of the primary medullary rays. 5 This specimen 

 therefore shows one of the chief distinguishing points between 

 Stigmaria and Stigmariopsis, Grand 'Eury. 



Among the earlier writers on Stigmaria, Steinhauer holds an 

 honourable position. His paper " On Fossil Reliquia of Unknown 

 Vegetables in the Coal Strata " G contains an admirable descrip- 

 tion of Stigmaria as far as then known. Among the specimens 

 figured by Steinhauer is a "termination" of a rhizome." 



2 PI. XIII. , fig. 2. Glasgow, 1793. 



3 Parkinson, Organic Remains of a former World, Vol. I., p. 43S, PI. 

 III., fig. 1. London, 1804. 



4 Martin, Petrificata Derbiensia ; or, Figures and Descriptions of Petri- 

 factions collected in Derbyshire. Wigan, 1S09. Pis. XL, XII. , and XII*. 



5 See also similar condition figured by Williamson, Monog. Stigmaria, 

 PI. XIV., fig. 69. 



c Steinhauer, Amer, Phil. Soc, Vol. L, New Series, ISIS, pp. 265-297, 

 Pis. IV. -VII. Philadelphia. 

 ? I.e., PI. IV., fig. 3. 



