DIVERSITY IX THE SCUTES OF CHELOXIA.* 



ROBERT E. COKER. 



With Text Figs. A to Q and Plates I to XIV. 



CONTENTS. 



PAGE 



Introduction 2 



Character of the Diversity 2 



Some Recent Views Regarding the Phylogenetic Significance of Nor- 

 mal and Abnormal Scutes 5 



Use of Terms 9 



Part I. Malaclemmys 13 



Section 1. Observations 20 



Section 2. Review of Observations 20 



Inframarginals 20 



Interplastrals 21 



Plastrals 22 



Marginals 23 



Nuchal 24 



Costals 24 



Neurals 28 



Section 3. Adjustment of Neurals and Costals 33 



Section 4. Age, Sex, Symmetry 43 



Summary 43 



Part II. TlialassochcJys carctta (L) 46 



Section 1. Introduction 46 



Material 46 



Conditions of Development 48 



Explanation of Tables 49 



Section 2. Observations on Diversity 50 



Section 3. Review of Observations 61 



Marginals 61 



Supra-Marginals 62 



Nuchal 62 



Costals 62 



*This paper was completed in June, 1906. While unavoidable circumstances 

 have prevented its earlier appearance, the text has had no material alteration. 



The .Touenal of Morphology. — Vol. 21, No. 1. 



