Sedimentary Rocks. • 5] 



of minute faults, rarely with a throw of mucli more than an 

 inch. 



Such is the nature of the Upper Ordovician rocks that it is 

 usually difficult to collect graptolites sufficiently well preserved 

 to enable specific identifications to be made with any confidence. 

 Moreover, so varied are the appearances which. a form such as 

 Diplograptus can assume with different angles of compression, 

 that even with favourable material diverse views may be taken. 

 Lastly, except for generic purposes, the mere outline of the 

 rhabdosome is of little value when dealing with Upper Ordo- 

 vician graptoljtes. 



Collections at all extensive have been made from only a few 

 outcrops. Most localities, however, are enormously rich in indi- 

 viduals. Lists of identified graptolites from a few typical locali- 

 ties will give some idea of the fauna. Ba 64, on Jackson's Creek, 

 north of Sunbury, yielded — 



Diplograptus, spp. including forms with a dilated virgula. 

 Climacograptus bicomis, J-. Hall. 



„ ,, var. pcltifer, Lapworth var. 



Dicranograptus ramosus, J. Hall. 



,, ziczac, Lapworth, or D. furcatus, J. Hall. 



Dicellograptus cf. sextans, J. Hall. 



,, cf. elegans, Carruthers. 



Glossograptus, sp. 

 Leptograptus ( ?). 

 The identification of the last genus is doubtful. Dr. Hall 17 has 

 recorded a Leptograptus from Lancefield, but recognised 18 that 

 it was not a typical member of the genus, and neither his figure 

 nor description of L. antiquus seems to present the characteristics 

 of the genus as described by English 19 and American 20 authori- 

 ties. Leptograptus is elsewhere an Upper Ordovician genus and 

 "has been recorded by Dr. Hall from the Upper Ordovician shales 

 of the Matlock district. 



Ba 67, at the junction of Riddell's and Jackson's Creek, is won- 

 derfully rich in beautifully preserved forms, so that one cannot 

 but regret the absence of the Dicranograptidae. We record — 



Diplograptus — several species, one of which is very com- 

 mon, and is recorded by McCoy 21 (probably er- 

 roneously) as D. pristis, Hisinger sp. 



17. 



9, p. 166, Plate XVII., Figs. 5 and 6. 



18. 



10, p. 440. 



19. 



11, P. 104. 



20. 



12, p. 260. 



21. 



1, Dec. 1, p. 11, PI. I., Fig. 6. 



5 a 



