On the " Cirripede'' Plumulites. 123 



that they would be useless for the purpose suggested by 

 Prof. Lefroy. Mr. Hamm entirely agrees with this 

 con elusion." 



The opinion of Mr. J. E. Collin, F.E.S., a wel]-kno\vn 

 student of and authority upon British Diptera, is precisely 

 the same as that of Prof. Poulton; like the present writer, 

 Mr. Collin has never met with even a solitary case of 

 Scatophaga preying upon Calliphora. 



Finally, Lt.-Col. J. W. Yerbury, whose experience as a 

 collector of our native Diptera is absolutely unique, and who 

 speaks with authority derived from thirty years' observation 

 of predaceous flies in the field, while admitting that such a 

 tiling may occasionally happen, has never observed an 

 instance of the Blow-fly being attacked by any species of 

 Scatophaga, and therefore considers Prof. Lefroy's assertion 

 to be at variance with facts. 



It would apjjcar, then, that if it be possible to discover a 

 natural means of control for the Sheep Blow-fly pest in 

 Australia, we must look elsewhere than to the Yellow 

 Dung-fly to find it. In any case, quite apart from tlie 

 negative evidence adduced above, which seems to the writer 

 to be reasonably conclusive, it is difficult to understand wh; t 

 advantage could possibly accrue from the introduction into 

 Australia of a British insect, which, though abundant in 

 these islands, is scarcely more so than its supposed victim. 



VII. — The '■'■Cirj'ipede''' Plumulites in the Middle Ordovician 

 Rocks of Esthouia. By Thomas H. Withers, P. G.S. 



(Published by permission of the Trustees of the British Museum.) 



Through the researches of F. Schmidt (1881-82), and the 

 laterworkof E. Koken(1897), J. H. Bonnema (1909), R. S. 

 Bassler (1911), and H. Bekker (1919), the Kuckers Stage 

 (C^ of Schmidt) of the Middle Ordovician rocks of Esthonia 

 and its fauna, particularly the Gastropoda, Trilobita, Ostra- 

 coda, and Polyzoa, are fairly well known. The Kuckers 

 Stage is represented in the neighbourhood of Kuckers, 

 10 km. N.W. of Jewe Station, Esthonia, by a white or 

 greyish-yellow limestone or marl, with intercalated layers 

 of soft bituminous shale generally of a rusty-brown or 

 amber colour. Phacops (Chasmops) odini is the charac- 

 teristic fos^sil, but numerous otl.er Trilubitcs occur, and 



