TABLE OF N T E iN T S . 



PART III. — DISCOPIIOE.E. 



CHAPTER I. 



DISCOPHOR.E IN GENERAL. 



Skctiox 1. Structure of the Dhcophor(t. — Natiival limits 

 of the order. Discophora; plianerofarpit Escli., Stegan- 

 ophthalmata Forbes, Acraspeda Gegenh. p. 3-G. 



Section 



Suh-orders of the Dixcophorce proper. — 



Their limitation. How families differ from sub-orders. 

 RItizoxtomea, Sema'ostomcce, Haptostomca. p. 7-9. 



CHAPTER II. 



THE GENUS AURELIA AND ITS SPECIES. 



Section 1. General remarks. — Different modes of study, 

 and sub-divisions of our science. p. 10-12. 



Section i. Formation and growth of Aurelia flavidula, 

 includinr/ comparitons with Cyanea arctica. — The egg 

 of Aurelia flavidula. The planula of Aurelia flavidula. 

 The egg of Cyanea arctica. The planula of Cyanea 

 arctica. The scyphostonia of Aurelia and Cyanea. 

 Histology of the scyphostonia. The strobila of Aurelia. 

 The ephyra of Aurelia. Structure of the eye, by Prof 

 H. J. Clark. The lasso-cells and their sj)ecial struc- 

 ture, p. 12-51. 



Section 3. Structure of the adult Aurelia flavidula. — 

 Symmetry of the body. Primary number of identical 

 segments. Ambulacral and interandxilacral systems. 

 The young and the adult. Compared to Echinoderms. 



p. si-e.?. 



Section 4. Homological relations of Aurelia ami Echi- 

 noderms. — The Coelenterata and Echinodermata built 

 upon the same plan. Arrangement of their sphero- 



mercs. Comparison of Aurelia with Echinarachnhis. 

 The radiating tubes of the Acalcphs and Echinoderms. 

 p. 63-72. 



Section 5. Closer affinities of Aurelia. — Resemblance 

 between the young and the ^Eginidas, while the adult 

 approximates the Rhizostomea;. p. 72-75. 



Section 6. Habits of A urelia. — Its appearance in the 

 spring and disappearance in the autumn ; passes the 

 winter in a larval condition. p. 75-78. 



Section 7. Nomenclature of Aurelia. — The young and 

 the adult, in various states of preservation, referred to 

 many genera, supposed to be distinct, but all of which 

 must now be suppressed. p. 78 and 79. 



Section 8. Peculiarities of the Aurelida' «.« a family. 



— Its special pattern. p. 80. 



Section 9. Generic characters of Aurelia, and specific 

 characters of the Aurelia flavidula of North America. 



— Comparison with the European Aurelia aurita. 

 Enumeration of the species of tliis genus. p. 81-8G. 



CHAPTER III. 



THE GENUS CYANEA AND ALLIED GENERA. 



Section 1. General description of Cyanea arctica. — 

 Difficulties in describing Acalephs. Misuse of names 

 to designate their ])arts. p. 87-90. 



Section 2. The abactinal system of Cyanea. — Imper- 

 fection of older illustrations. Structure and appear- 

 ances, p. 91-95. 



Section 3. The tower floor of Cyanea, and its connection 

 with the upper floor. — Actinal system. Homology of 

 the parts. Essential elements of the structure of Cya- 

 nea. Large amount of structural water in Acalcphs. 

 Broad and narrow pouches alternating. Concentric 

 and radiating folds. Tentacles. Genital pouches. 



