PREFACE 



Parts 3, 4, and 5 of Volume 1, Bulletin 82, include the systematic discussion of the 

 species and higher groups of living comatulids, or unstalked crinoids. Part 3, published 

 on March 21, 1931, included the account of the superfamily Comasterida. Part 4a, 

 published on August 5, 1941, included the account of the superfamily Mariametrida, 

 with the exception of the family Colobometridae. Part 4b, published on October 9, 

 1947, contained the account of the family Colobometridae of the superfamily Maria- 

 metrida, and of the families Tropiometridae, Calometridae, Ptilometridae, and Aster- 

 ometridae of the superfamily Tropiometrida. Part 4c, the. present one, is the concluding 

 section of part 4. It is a continuation of Part 4b and includes the account of the two 

 remaining families of the Tropiometrida, the Thalassometridae and the Charitomet- 

 ridae. Part 5, the concluding part of Volume 1, will be an account of the entire sub- 

 order Macrophreata. 



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