TABLE OF CONTENTS. 



MORPHOLOGY. 



Page 



CHAPTER I. — The Zoological History of the Blastoidea 1 



CHAPTER II.— The Stem and Calyx 9 



A. The Stem 9 



B. The Calyx 10 



C. The Basals 12 



Dorsal and radial axes 13 



Ridges on the basal cup l(i 



Supposed under-basals of Blastoids IS 



D. The Radials 22 



Homologies of the radials ' . 26 



E. The Deltoid Plates or Interradials 28 



Deltoids of Heteroschisma 30 



„ Stephanocrinus '51 



„ Elaacrinus 35 



„ Troostocrinus 36 



F. On the Homologies of the Deltoid Plates 37 



G. Irregularities of the Calyx., and Monstrosities 39 



CHAPTER III.— The Ambulacra 42 



A. The Lancet-plate and its Internal Relations VI 



Under lancet-plate 44 



Lancet-canal 50 



(Esophageal ring 52 



B. The Superficial Markings of the Lancet-plate 54 



C. The Side Plates 56 



D. The Outer Side Plates 61 



E. The Pinnules 63 



F. The Covering Plates of. the Ambulacra 63 



b 2 



