108 DIFFICULTIES AND SOURCES OF ERROR. [CH. 



spore-like bodies appear on close examination to be made up of 

 finely comminuted particles of tissue, and in all probability 

 they are the coprolites of some xylophagous animal. Examples 

 of such coprolites are shown in fig. 24 A ^ and in fig. 24 B 

 an interesting manner of occurrence of these misleading bodies 

 is represented. The framework of cells enclosing the nest of 

 coprolites in fig. 24 B, represents the outer tissues of a Lepi- 

 dodendroid or a Sigillarian leaf; the inner tissues have been 

 destroyed and the cavity is now occupied by what may possibly 

 be the excreta of the wood-eating animal. 



Some of the oval spore-like structures met with in plant 

 tissues may, as Renault has suggested, be the eggs of an 

 Arthropod I In a section of a calcareous Coal- Measure nodule in 

 the Williamson collection (British Museum)^ there occur several 

 fungal spores or possibly oogonia lying among imperfectly 

 preserved Stigmarian appendages. Associated with these are 

 numerous dark coloured and larger bodies consisting of a cavity 

 bounded by a simple membrane ; the larger bodies may well be 

 the eggs of some Arthropod or other animal. 



In looking through the collections of Coal-Measure plants 

 in the Museums of Berlin, Vienna and other continental towns, 

 one cannot fail to be struck with the larger size of many of the 

 specimens as compared with those usually seen in English 

 Museums. The facilities afforded in the State Collieries of 

 Germany to the scientific investigator may account in part 

 at least for the better specimens which he is able to obtain. 

 It would no doubt be a great gain to our collections of Coal- 

 Measure plants if arrangements could be made in some collieries 

 for the preservation of the finer specimens met with in the work- 

 ing of the seams, instead of breaking up the slabs of shale and 

 consigning everything to the waste heaps. There is one more 

 point which should be alluded to in connection with possible 

 sources of error, and that is the essential importance of ac- 

 curacy in the illustration of specimens, especially as regard 



1 Williamson has drawn attention to the occurrence of such borings and 

 coprolites in Coal-Measure plant tissues. E.g. Williamson (80) PI. 20, figs. 65 

 and 66. 



2 Renault (96) p. 437. ^ gii^e No. 1923 in the Williamson collection. 



