CONTRIBUTIONS TO THE ANATOMY OF THE HIRUDINEA. 421 



brought to the Zoological or Botanical Gardens. I have, how- 

 ever, obtained one specimen from a ditch by the side of the 

 Epsom and Leatherhead Railway. 



Literature. — The literature of the group is enormous in its 

 quantity, and extends back to the middle ages. The importance 

 of leeches in medicine induced numerous observers to work at 

 the group. 



I do not propose to deal with any of the older writers, 

 except in one or two special cases, but to take as my basis 

 Moquin-Tandon's classical work ' Monographic de la famille 

 des Hirudinees,' 1846. Reference is there made to all the 

 older literature. 



It is since this date, however, that histological observations of 

 any value have been made, Leydig taking the lead in this respect. 



I append a list of the chief works published since 1846, and 

 those to which I shall constantly make reference. The arrange- 

 ment is chronological. 



1. Leydig. — " Zuni Circulations und Respirations System von Nephelis 



uud Clepsine." * Berichte von der Konigliclien zootomischen Anstalt 

 zu Wurzburg,' Leipzig, 1S49. 



2. Leydig. — "Zur Anatomie von Piscicola geonielrica mit tiieil- 

 weiser Vergleicimng anderer einheimischer Hirudineeu," ' Zeitschrift 

 flir Wissenscliaftliche Zoologie,' Band 1, 1849. 



3. Budge. — "Clepsine bioculata, Saviguy," ' Verhandlungen des 

 naturhistorischen Vereins der preussischeu Rheinlande,' 1849. 



4. Gratiolet, Pierre. — " Recherches sur Torganisation du Systeme 

 Vasculaire de la Sangsue Medicinale et I'Aulastome Vorace" (prelimi- 

 nary note), ' A.nnales des Sciences Naturelles ' — " Zoologie," xiv, p. 

 189, 1850. 



5. Leydig, Franz. — " Anatomischesueber Branchellion und Pontob- 

 della," • Zeitschrift fiir w, Zoologie,' Bd. 4, 1851. 



6. Quatrefages, A. de. — "Etudes sur les types inferieurs de Tembranche- 

 ment des Anneles. Memoire sur le Branchellion de D'Orbigny," 



' Annales des Sciences Naturelles '— " Zoologie," 3 Ser., 17, 1852. .' ^ 



7. ^brard, Le Dr. E. — ' Nouvelle Monographic des Sangsues Medicin- 

 ales,' Paris, 1857. 



8. Gratiolet, Pierre. — " Recherches sur I'organisation der Systeme 

 Vasculaire dans la Sangsue Medicinale et I'Aulastome Vorace," ' An- 

 nales des Sciences Naturelles' — " Zoologie," 4 Ser., 17, 1862, 



