CONTRIBUTIONS TO THE ANATOMY OF TEE HIEUDINEA. 419 



Contributions to the Anatomy of the Hirudinea. 



By 



Alfred Gibbs Bourne, B.Sc. I^ond., 



Assistant Professor of Zoology and Comparative Anatomy, University College, 



London. 



With Plates XXIV— XXXIV. 



Contents. 

 i. Introduction. 



ii. External Characters. 



iii. Skin — Epidermic Glands — Sensory Cells — Dermis. 



iv. Muscles — Proboscis. 



V. Connective and Vasifactive Tissues— Endocytic and Paracytic Spaces. 



vi. Blood and Blood-vessels — Ccelomic Spaces — Ccelosis. 

 vii. Nephridia. 

 viii. Alimentary Canal. 



ix. Phylogenetic Conclusions. 



i. Introduction. 

 In addition to recording my own observations, which have 

 extended over a period of four years, I have endeavoured to sift 

 and summarise previous observations and to insert them, so as 

 to enable me to give a connected account of the systems with 

 which I have dealt, for the whole group. 

 The genera with which I deal are : 

 Rhynchobdellid^ — 



Pontobdella, Leach, 1815. 

 Piscicola, Blainville, 1818. 

 Clepsine, Savigny, 1817.^ 



^ I have retained the name Clepsine because it has such a wide-spread use, 

 but Glossiphonia, Johns., 1816, appears really to have the precedence. 



