REPORT ON THE FORA MINIFER A. 
747 
The claims of the numerous Tertiary Heterostegince to the specific positions accorded 
to them by palaeontologists, are in almost every case problematical. But without 
entering into this question, it may be broadly stated, that fossil specimens, identical in 
all important characters with the recent species, occur as far back as the limestones of 
the Eocene period. 
Nummulites, Lamarck. 
Helicites, Guettard [1770], Burtin, Defrance, Blainville. 
Nautilus , pars, Forskal [1775], Eicktel and Moll. 
Camerina, Bruguiere [1792], Bose, Cuvier. 
Phacites, Blumenbach [1799], 
Nummulites, Lamarck [1801], Roissy, Defrance, Blainville, Caillaud, Boubee, Ehrenberg, 
Deshayes, Reuss, Joly and Leymerie, d’Archiac and Haime, Bellardi, Gemmellaro, Carter, 
Verbeek, Hantken, de la Harpe, Jones, &c. 
Discolithes, pars, Eortis [1802], 
Lenticulites, pars, Lamarck [1804], Scblotbeim, Defrance, Blainville, Bronn, d’Archiac, 
Rutimeyer. 
Numulites, Lycophris, Rotalites, Egeon, Montfort [1808], 
Nummularia , Parkinson [1811], Sowerby, Rutimeyer. 
Lenticulina, pars, Lamarck [1822], Defrance, Blainville, Reuss. 
Nummulina, d’Orbigny [1826], Bronn, Micbelotti, Carpenter, Schafhautl, Rutimeyer, Rouault, 
Savi and Menegbini, Carter, Costa, Williamson, Jones and Parker, Bornemann, Karrer, 
Ivaufmann, Brady, Terquem, &c. 
Amphistegina, pars, Reuss [1855], Carpenter. 
The genus Nummulites exemplifies the highest type of structure attained by the 
perforate calcareous Foraminifera. It is, however, a genus of which our knowledge is 
derived almost entirely from fossil specimens, and its still living representatives, which 
are • limited to one or two inconspicuous forms, afford no sufficient standpoint for a 
general survey of its characters or history. Of recent years the study of Nummulites 
and their immediate allies, at any rate so far as affects their comparative morphology and 
systematic grouping, has been chiefly conducted by specialists, who have had peculiar 
facilities for obtaining the fossil forms, which exist in enormous numbers in the rocks of 
the earlier portion of the Tertiary epoch. The literature of the genus is probably more 
extensive than that of any other group of Protozoa of similar zoological importance ; and 
amongst the authors to whose labours we owe our present accurate acquaintance with 
the various phases of its history, the names of Joly and Leymerie, cTArcliiac and 
Haime, Vfilliamson, Carpenter, Carter, Jones and Parker, von Hantken, and de la Harpe, 
are the most prominent. The chief desiderata still remaining are the judicious reduction 
of the number of so-called species, and the simplification of the nomenclature of the 
group. 
The typical Nummulite has the form of a biconvex disk, the two sides of which are 
equal or nearly so, formed of a number of convolutions, each completely enclosing that 
