viii CONTENTS 



Part III. Morphology of the orthoid shell — Cont. Page 



Morphology of the dorsal interior 34 



Notothyrial platform 34 



Denticles and sockets 34 



Denticles 34 



Sockets 34 



Cardinalia 34 



Cardinal process 34 



Brachiophores or brachial apparatus 37 



Cruralium and pseudocruralium 39 



Septa 39 



Musculature 39 



Pallial markings 40 



Microstructure of the shell 41 



Exopuncts 42 



EndopunctEC 42 



Value of punctation in taxonomy 42 



Old-age characters 42 



Part IV. The genera of the suborder Orthoidea 43 



Superfamily Orthacea 43 



Family Nisusiidae 43 



Nisusia 44 



Jamesella 46 



Family Protorthidje 46 



Protorthis 46 



Loferia 47 



Family Billingsellidas 48 



BUlingsella 48 



Family Eoorthidje 50 



Witnanella 50 



Eoorthis 51 



Otusia 52 



Bohemiella 52 



Oligomys 53 



Family Finkelnburgiidse, nov 54 



Orusia ^ 54 



Finkelnburgia 55 



Family Plectorthidas 56 



Subfamily Plectorthinx 57 



Plectorthis 57 



Hebertella 59 



Mimella 61 



Schizofhorella 62 



Doleroldes 63 



Subfamily Cyclocoeliinas 64 



Cyclocaelia 64 



Subfamily Platystrophiins 64 



Platystrofhia 64; 



Mcewanella 69 



