CONTENTS. xiii 



CHAPTER XVIII. 



Echinoidea General characters Anatomy of Echinus Divisions o r 



Echinoidea, ......... 193-201 



CHAPTER XIX. 



Asteroidea and Ophiuroidea General characters of the Asteroidea 

 Divisions of the Asteroidea General characters of the Ophiuroi- 

 dea Families of the Ophiuroidea, ..... 201-207 



CHAPTER XX. 



Crinoidea, Cystoidea, and Blastoidea General characters of Crinoi- 



dea Of Cystoidea Of Blastoidea, . , . , ;. . 207-218 



CHAPTER XXI. 



Holothuroidea General characters Sub-orders of Holothuroi- 

 dea, . , .-' . . . .~" . . . 218-221 



CHAPTER XXII. 



Distribution of Echinodermata in space Distribution of Echinoder- 

 mata in time Crinoidea Blastoidea Cystoidea Astercidea 

 Ophiuroidea Echinoidea Holothuroidea Literature of Echino- 

 dermata, . ':' V t- :;.-< : -" ...... 222-226 



CHAPTER XXIII. 



General characters of the Annulosa Divisions of the Annulosa 

 General characters of the class Scolecida Entozoa Platyelmia 

 Tseniada Structure and development of the Tapeworm 

 Hydatids, . -, ' , , "" ...... 227-236 



CHAPTER XXIV. 



Trematoda and Turbellaria General characters of the Trematoda 

 General characters of the Turbellaria Planarida Nemertida 

 Balanoglossus and Tornaria Pelagonemertidse, . . 237-242 



CHAPTER XXV. 



Nematelmia Acanthocephala Gordiacea Nematoda Parasitic 



Nematoids Free Nematoids, ...... 242-248 



CHAPTER XXVI. 



Rotifera General characters of the Rotifera Affinities of the Roti- 



fera Literature of Scolecida, ...... 248-254 



CHAPTER XXVII. 



General characters of the Anarthropoda Class Gephyrea General 



characters of the class Annelida, 254-259 



CHAPTER XXVIII. 



Divisions of the Annelida Hirudinea Oligochseta Tubicola 

 Errantia Distribution of the Annelida in time Class Chseto- 

 gnatha Literature of Anarthropoda, .... 260-273 



