CHAPTER 3 



A SURVEY OF THE GROUP 



(a more detailed systematic survey is given in the appendixes) 



1. Classification 



The following is the scheme of classification adopted in this w^ork : 

 Order Hirudinea 



Suborder Acanthobdellae 

 Suborder Rhynchobdellae 

 Family Glossiphoniidae 

 Family Piscicolidae (= Ichthyobdellidae) 

 Suborder Gnathobdellae (= Arhynchobdellae) 

 Family Hirudidae 

 Family Haemadipsidae 

 Suborder Pharyngobdellae 

 Family Erpobdellidae 

 Family Trematobdellidae 

 Family Semiscolecidae 

 The Acanthobdellae comprises the single genus Acanthobdella 

 which is in many ways intermediate between the Oligochaeta and 

 the Hirudinea. Chaetae are present in five anterior segments, 

 there is no anterior sucker, and the coelom is not entirely obliterated. 

 Acanthobdella is a small fish parasite from Lake Baikal (Fig. 12). 

 The Rhynchobdellae are jawless and are those leeches which 

 utilize a proboscis to penetrate the tissues of the host. There are 

 distinct blood vessels in the body and the blood is colourless. They 

 are marine and freshwater forms, none is terrestrial. The group 

 is divided into two families: the Glossiphoniidae which are 

 dorso-ventrally flattened leeches confined to freshwater and having 

 an anterior sucker which is continuous with the outline of the body, 

 and the Piscicolidae which are cylindrical mostly marine leeches, 

 having an anterior sucker which is bell shaped and clearly marked 

 off from the body. 



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