44 FORAMINIFERA 



referred to Placopsilina, on crinoids from the Upper Silurian, 

 three of which at first glance would appear to be Nodosarias and 

 in section might easily be mistaken for this genus. According 

 to Terquem, however, they were attached forms. He also refers 

 specimens questionably to Orhulina, Lagenulina, Cristellaria, 

 Fusulina, and Globigerina. Keeping refers material from the 

 Silurian of Central Wales to Dentalina, Rotalia (?), and 

 Textularia. The figures of the last-mentioned genus at least 

 seem to be correctly identified. There are other scattered 

 records from the pre-Carboniferous but these are enough 

 perhaps to indicate that the foraminifera, except from the 

 material from the Malverns in the Cambrian, are not at all 

 abundant. The first abundant species which can be unquestion- 

 ably referred to the foraminifera is Spirillina or at least a 

 planispiral form with a proloculum and long undivided second 

 chamber. The other records indicate that the Lagenidae and 

 Textulariidae were also already developed. 



Beginning with the Carboniferous, foraminifera are often 

 abundant. In the Pennsylvanian of America there are rich 

 faunas with abundant specimens. Arenaceous forms almost 

 completely predominate. The Saccamminidae, Hyperamminidae, 

 Reophacidae, Ammodiscidae, Lituolidae, Textulariidae, Verneuil- 

 inidae,Fusulinidae,Trochamminidae, Orbitolinidae, and Placopsi- 

 linidae, a majority of the arenaceous group, are present and 

 some of them well developed in the Pennsylvanian. Some of 

 the Lagenidae are possibly present, and the beginnings of the 

 Miliolidae and Camerinidae. There are a few other groups 

 recorded but they should be carefully checked as they rest upon 

 single specimens in some cases. Altogether the Palaeozic fora- 

 minifera are predominantly or almost exclusively arenaceous 

 and this condition continues on into the Permian where some of 

 the lines of development reach their climax and become extinct. 



Triassic foraminifera are extremely rare. Those that seem to 

 be well enough preserved for generic identification are almost 

 entirely genera which have already appeared in the Palaeozoic. 



The Jurassic is characterized by the dominance of the 

 Lagenidae. These become very abundant and develop very many 

 species. Arenaceous groups persist and at some horizons are 

 abundant and the first records of most of the other arenaceous 

 families like the Astrorhizidae and Rhizamminidae appear. This 



