REPORT OF THE DIRECTOR IO,l6 113 



Silurian — Recent! '. . Acmaea, Eotrochus, Patella, Pleurotomaria 



(subgenera, see p. 116), Trochus (sub- 

 genera), Turbo (?) 



Devonian — Triassic Naticopsis 



Devonian — Cretaceous Zygopleura 



Carboniferous ■ — Jurassic .... Bourgetia 



Carboniferous (?) — Tertiary. Pseudomelania 



Carboniferous — Recent! Aetaeonina, Emarginula, Fissuridea (?), (Fis- 



surella auct.), Vermicularia (VermKus 

 auct), (?) (Subgenera) 



Triassic — Cretaceous Amberleya, Cylindrites, Fibula 



Triassic — Tertiary Discohelix 



Triassic — Recent! Astralium (subgenera)., Calliostoma, Cylichna, 



Delphinula, Eulima, Epitomium (sub- 

 genera), Monodonta, Natica (subgenera), 

 Nerita (?), Neritopsis, Niso, Turritella 

 (subgenera) 



Jurassic — Tertiary Pileolus, Tornatellaea 



Jurassic — Recent Aporrhais (subgenera), Bullaria (?), Bullina, 



Cerithium (subgenera), Cypraea, Etallonia, 

 Fusus, Hydatina, Liotia, Littorina, Mathilda, 

 Melania, Rimula, Rissoa, Rissoina, Scurm, 

 Solarium 



Cretaceous — Recent Acteon, Ancilla, Bithinia, Calyptraea, Chry- 



sodomus, Clavatula (subgenera), Cominella, 

 Conus (subgenera), Crepidula, Diastoma, 

 Erato, Fasciolaria, Galeodea, Hipponyx, 

 Hydrobia, Latirus, Megalomastoma, Melan- 

 opsis, Murex (subgenera), Nassa, Nyctilo- 

 chus (Tritonium), Oliva, Phasianella, 

 Philine, Pleurocera, Pseudoliva, Potamides 

 (subgenera), Pyramidella, Pyrula, Rapana, 

 Rimella, Ringicula, Scaphander, Siliquaria, 

 Strombus, Tonna, Tudicla, Turricula, Turris 

 (Pleurotoma) (subgenera), Typhis, Vivi- 

 para (subgenera), Xenophora 



The Pulmonata contain as persistent genera : 



Jurassic — Recent Auricula, Carychium, Lymnaea, Planorbis, 



Physa 

 Cretaceous — Recent Glandina, Megaspira 



There are also persistent types among the Pteropoda, namely : 

 Cretaceous — Recent Clio (subgenera), Vaginella 



Conularia is recorded as ranging from Ordovician-Jurassic ; 

 Hyolithes from Cambrian to Permian. 



The Cephalopoda furnish the following persistent genera, all 

 among the Nautiloidea : 



Ordovician — Devonian Clinoceras, Cyclostomiceras, Zitteloceras 



Ordovician — Carboniferous . .Actinoceras (subgenera), Geisonoceras, Loxo- 



ceras, Poterioceras, Spyroceras 



