1887.] 



ON CYCLESTHERIA HISLOPI. 



61 



Table of Contents. 



Pag. 



Intro ducti on 3 



I. Generic and Specific Characters, with Kemarks on Affi- 

 nity and Synonymy 6 



II. Morphology and Anatomy 10 



A. The Shell 10 



B. The Body and its Appendages 12 



a. The Head 13 



b. The Cervical Division, or Neck 19 



c. The Trunk 21 



d. The Tail 26 



C. The Inner Organa 27 



a. The Nervous System 27 



b. The Digestive System 23 



c. The Circulatory System 29 



d. The Genital System. . 30 



III. Physiology 32 



A. Motion 32 



a. The Locomotion 32 



b. The Partial Motion 33 



B. Sensation 38 



C. Digestion 40 



D. Circulation 41 



E. Bespiration 43 



F. Secretion 43 



G. Propagation 44 



IV. Ontogeny - 46 



a. Development of the Summer-eggs 46 



b. Development of the Winter-eggs 55 



V. Biological Observations 56 



IV. Occ urrence and Distribution 60 



