PREFACE. 



more restricted, or very rarely a more extended meaning 

 than its original proposer applied to it. If this was not 

 allowed, many new names must be added to the list of 

 genera, which is already so overburdened with synonyma. 



In those cases where the two sexes of the same species, 

 or any particular individual state or variety belonging to it, 

 have been differently named, the names belonging exclusively 

 to the state or individual described are placed after the refer- 

 ence to the specimens to which they apply. 



To determine with accuracy the names and synonyma of 

 the species, the various specimens, skeletons and other re- 

 mains of these animals in the museums of the College of 

 Surgeons of London and Edinburgh, of the Zoological So- 

 ciety, and of the different local museums, especially those of 

 Haslar, Norwich, Bristol, Liverpool, &c., and the various 

 continental museums of Paris, Leyden, Berlin, Vienna, and 

 Frankfort, have been personally examined, and in some cases 

 the specimens contained in those museums have been sent 

 to the Museum, so that they could be actually compared 

 with the specimens in the Museum Collection. 



JOHN EDWARD GRAY. 



Oct. 1, 1850. 



