ABBREVIATIONS. 



A. M. N. H. Annals and Magazine of Natural History. 



G. M. Geological Magazine. 



Q. J. G. S. Quarterly Journal of the Geological Society of 

 London. 



Salter, Cat. Catalogue of the Cambrian and Silurian Fossils in 

 the Geological Museum of the University of Cam- 

 bridge, by J. W. Salter. 1873. 



