i897. THE LITERATURE OF FOSSIL OSTRACODS. 183 



subject and to show the necessity for further work. The valves of 

 Ostracoda are so common in certain beds as to rank among the rock- 

 formers, and they present usually a delicacy and intricacy of ornament 

 and hinge structure which admits of their easy differentiation. The 

 smooth forms present many difficulties ; but, with care, specimens 

 can be found which show the hingements, and thus permit deter- 

 mination of the genus, though the determination of the species is much 

 more difficult. What is really wanted is careful collecting from some 

 well-known section, or series of sections, of any geological formation, 

 and this would be of greater importance than the casual description of 

 various species taken at random from many localities, though the 

 latter is, of course, a very necessary work. 



C. Davies Sherborn. 

 540, King's Road, Chelsea. 



