Xll CONTENTS. 



CHAPTER XVII. BRACHIOPODA continued. PAGE 



IV. General considerations . . . . 78 



Literature . . . . ... 83 



Appendix General considerations on the Molluscoida . 84 



Rhabdopleura and Cephalodiscus . . ... 88 



Literature . . . . ... 89 



CHAPTER XVIII. ENTOPROCTA. By K. HKIDER . . . 91 



Embryonic development and larva . . ... 91 



Metamorphosis . . . ... 96 



Asexual reproduction . . . ... 98 



General considerations . . . . 100 



Literature . . . . ... 102 



CHAPTER XIX. CRUSTACEA. By K. HBIDER . . . 104 



Systematic . . . . ... 104 



I. Development of the embryo . . . . 104 



1. Oviposition, care of the brood . ... 104 



2. Cleavage and formation of the blastoderm . . .106 



VitclHne membrane . . . 106 



Types of cleavage . . . . . 108 



Blastodermic cuticle, larval integument . . .118 



Paracopulation . . . . . 119 



3. Formation of the germ-layers . . . .119 



A. Copepoda . . , . 119 



. Phyllopoda . . . ... 123 



C. Cirripedia . . . . . 126 



D. Decapoda . . . . . 127 



E. Schizopoda . . . . . 134 



F. Arthrostraca and Cumacea . . 136 



G. General considerations . ... 141 



Types of development of the enteron . . .143 



Formation of the mesoderm . ... 145 



4. Development of the external form of the body . . .146 



A. Entomostraca . . ... 146 



B. Arthrostraca and Cumacea . . . .148 



Dorsal organ . . . 150 



C. Leptostraca, Schizopoda, and Decapoda . . . 152 



5. Formation of the organs . . ... 159 



A. External integument . . . 159 



B. Endoskeleton . . ... 160 



C. Nervous system . . . ..160 



Development of the brain . . . .162 

 Primary segmentation of the cephalic region . .164 



D. Sensory organs . . . 167 



Development of the compound eye . . .168 



Development of the auditory organ . . .172 



E. Gills . . . 172 



F. Intestinal canal . . . 173 



Entomostraca . . . . 174 



Decapoda . . . . 174 



Arthrostraca . . . 175 



G. Heart . .177 



