REPORT OF THE DIRECTOR I916 IO9 



Jurassic — Recent Astrorhiza, Rhabdammina, Marsipella, 



Bathysiphon, Rhizammina, Planorbulina, 

 Pulvinulina, Rotalia, Polystomella, Cornu- 

 spira, Nubecnlaria, Ophthalmidium 



Cretaceous — Recent Calcarina, Discorbina, Operculina, Sphaeroid- 



ina, Bolivina, Ellipsoidina, Chilostomella, 

 Allomorphina, Dimorphina, Hauerina, 

 Alveolina 



Not only the genera possess this remarkable persistence but 

 also many species persist, according to Parker, Jones, Brady, Bagg 

 and others, throughout a number of formations (see p. 126). In 

 general, the persistence of the Foraminifera surpasses that of all 

 other orders which are known in fossil condition. The Radiolar- 

 ians were probably as persistent in their genera but the group is 

 still very imperfectly known in its fossil representatives, especially 

 the Paleozoic. Their minute and delicate skeletons are, however, 

 known to have been as abundant and diversified in the past ages 

 as at present. 



The sponges, contrary to expectation, furnish but very few per- 

 sistent fossil types : 



Cambrian — Carboniferous . . . Hyalostelia 



Devonian — Cretaceous Peronidella 



Carboniferous — Jurassic Cnemidiastrum (Hinde) 



Carboniferous — Cretaceous ..Doryderma (Hinde) 



Triassic — Cretaceous Corynella, Raphidonema, Sestrostomella 



Jurassic — Tertiary Craticularia 



Cretaceous — Recent Cystispongia 



A great number are found among the corals: 

 Ordovician — Devonian Anisophyllum, Aulacophyllum, Columnaria, 



Halysites, Heliolites, Plasmopora 

 Ordovician — Carboniferous ..Amplexus, Aulopora, Cyathophyllum, Em- 



monsia, Favosites, Petraia 

 Silurian — Carboniferous Clisiophyllum, Strephodes, Syringopora, 



Zaphrentis 

 Carboniferous — Jurassic .... Chaetetes 



Triassic — Cretaceous Isastraea, Stylina 



Triassic — Tertiary Astrocoenia, Astraeomorpha, Calamophyllia, 



Dimorphastraea, Montlivaultia, Phyllo- 



coenia, Thecosmilia, .Dimorpharaea 



Triassic — > Recent Stephanocoenia 



Jurassic — Tertiary Comoseris, Cyclolites, Leptoria 



Jurassic — Recent Cladocora, Favia, Goniastraea, Orbicella, 



Stylophora, Trochocyathus, Thecocyathus 

 Cretaceous — Recent Caryophyllia, Ceratotrochus, Coelosmilia, 



Diploria. Lophosmilia, Sphenotrochus, 



Goniastraea, Porites, Turbinaria, Heliopora 



