APPENDIX B 173 



28. Abdomen rounded and not very distinct from trachelo- 

 some ; skin opaque Ottoniohdella 



— Abdomen broad, flattened and distinct from trachelo- 

 some ; skin transparent Oceanohdella 



29. Testes 4 pairs; posterior sucker tends to face postero- 

 dorsally Cryohdella 



— Testes 5 pairs ; posterior sucker faces postero-ventrally 



Platyhdella 



30. Annuli 14 per somite Carcinohdella 



— Annuli 16 per somite Notostomohdella 



Genera of Marine Leeches 

 WITH Some of the Species from the North Atlantic 

 AND Neighbouring Seas 



Particularly distinctive characters are given in italics. The 

 treatment is not exhaustive and only a selection of references is 

 cited. Species reliably recorded from Britain are marked by 

 asterisks. 



ARCTOBDELLA de Silva and Kabata 1961. Oral sucker 

 small, eyes 0, posterior sucker discoid, abdomen flattened and 

 smooth, annuli 3(6) but obscure, coelom fairly spacious and not 

 divided into lacunae, diverticula separate, ganglia 18+1 fused 

 anteriorly, testes 4 pairs. 



Arctohdella hranchiarum de Silva and Kabata. 10 mm long. 

 Gills of Drepanopsetta platessoides. Iceland. 



AUSTROBDELLA Badham 1916 (Ingram, 1957). Suckers 

 discoid, eyes 0-1 pair, abdomen flattened, smooth and forming 

 "shoulders" behind clitellum v^hich is not more constricted than 

 rest of trachelosome, annuli 3 (6), a contractile lacuna in dermis 

 throughout length of abdomen on each side and w^ithout separate 

 pulsatile vesicles or subdermal lateral lacunae but coelom other- 

 wise fairly typical, ganglia 21, testes 5 pairs. Two spp. from 

 Australia and Tasmania. 



Austrobdella anoculata Moore (1940). 5 mm long. Greenland. 



