CHAPTER XXVII 



ANNULATA AND HIRUDINEA 



Annulata — Hirudinea — Classification — Gnathobdellidae — Hirudinae — 

 Haemadipsinae — Remaining orders — References. 



PHYLUM ANNULATA AUCTORES. 



Metazoa with elongated bodies divided externally into a number 

 of rings which represent a division of the internal parts into seg- 

 ments or somites (metameres), usually with an extensive coelom. 

 Nervous system consists of a cerebral ganglion, with double com- 

 missure and ventral nerve cord. Organs of excretion in the form 

 of metamerically arranged pairs of nephridia. 



The only class of this phylum which contains animals of impor- 

 tance in tropical medicine is the Hirudinea or Discophora — i.e., 

 the leeches. 



CLASS HIRUDINEA Savigny, 1817. 



Annulata with oval bodies, showing a dorso-ventral flattening 

 and two suckers, one at each end. 



Remarks.— Leeches are of interest in the tropics, first because 

 they may be a considerable nuisance as ectoparasites— ^.g., land 

 leeches or Hcemadipsa ; and, secondly, they may be of considerable 

 danger to the health and even the life of a person as endoparasites 

 — -e.g., the water leeches, particularly Limn^j^ts. 



As ectoparasites they are apt to fasten on the legs of persons 

 going through grass or jungle. In fact, in Ceylon, while standing 

 on a piece of grass in certain parts of the low country, the leeches 

 can be watched converging from all quarters of the compass towards 

 the observer. 



Very often the bite is not noticed, and the leech or leeches may 

 have sucked a considerable amount of blood before any attention 

 is paid to them, and tales are told of persons feeling faint before 

 noticing that they were being attacked by these creatures. 



They are apt to get into the nose, naso-pharynx, or larynx with 

 drinking-water, and in this endoparasitic condition they may suck 

 blood and cause epistaxis or h?emoptysis, and this may go on to 

 such an extent that anaemia and even death may result. 



It is hardly possible to believe that they can live in the stomach, 

 for it is much more likely that they are at once killed by the gastric 

 juice and digested. 



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