APPENDIX B 



THE SYSTEMATICS OF 

 MARINE LEECHES 



By Professor E. W. Knight-Jones 

 Department of Zoology^ University College of Swansea 



The marine leeches constitute the greater part of the family 

 Piscicolidae. They are even less well known than the freshwater 

 and terrestrial forms, and it is not unusual to find undescribed 

 species. The last synopsis was that of Herter (1935) but new 

 forms have been described since. In this appendix a tentative 

 key to the marine genera of the world is followed by a list of 

 genera in alphabetical order, giving their characters and most of 

 their North Atlantic species. 



Marine leeches can seldom be collected to order but are often 

 found at sea or on dead fish and have to be fixed by whatever 

 method happens to be available. The technique of study is rather 

 different from that used with freshwater forms. Internal anatomy 

 is important and this can be observed by clearing in cedar wood 

 oil but better by sectioning. The intersegmental testes are a useful 

 guide to the limits of segments and make it possible to determine 

 the number of annuli per segment in a cleared specimen. Clearing 

 also reveals eyes, which may otherwise not be visible after death. 

 Good sections are obtained after narcotizing with menthol and 

 fixing in sea water Bouin. 



The following terms and abbreviations are used in the key and 

 descriptions : 



abdomen, body behind clitellum, often flattened dorso-ventrally ; 

 annuli, number of annuli per mid-body segment, the convention 

 3 (6) meaning that each of three annuli is faintly divided into two ; 

 coelom, refers to the coelom of the mid-body (testicular) region; 

 coelom typical, as in Piscicola, with dorsal, ventral, lateral and 



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