66 Bibliographical Notices. 
Gomphoceras, and the subgenus T’rocholites, with internal siphuncle, 
appears before Nautilus. 
Prof. Blake continues some further general observations and care- 
fully expressed views bearing on the origin and fixity of species and 
the theory of evolution, derived from the study of the Silurian 
forms, which afford a fair succession of the same class ; and therefore, 
so long as the surrounding circumstances remain the same, the pro- 
cess of evolution by indefinite variation should either be uniform, 
or should cease when the best adaptation to these conditions had 
been acquired. He considers that the present study of Silurian 
Cephalopoda offers no contradiction or difficulty, but rather affords 
aid, if not as great as could be desired, yet as much as could be 
expected, to the general theory of evolution. 
Hitherto the species of Silurian Cephalopoda were to be sought for 
in the different works of Murchison, M‘Coy, Salter, and others ; we 
have now, however, a monograph of the British forms, systematically 
arranged, carefully described, well illustrated, and replete with 
important observations on the structure, affinities, and modifications 
of the group, indicating throughout not only a great amount of 
labour, but of critical acumen and care displayed in the determina- 
tion of the typical and varietal forms, thus supplying a much- 
wanted treatise on the early history of this group of Mollusca, and 
adding a valuable contribution to paleeontological literature. 
Catalogue of the Fossil Foraminifera in the British Museum (Natural 
History). By Prof. T. Rupsrr Jones, F.R.S., F.G.8., &. 8vo. 
Pp. i-xxiv and pp. 1-100. London: Printed by order of the 
- Trustees, 1882. 
Fottowr1ne the work of Dr. H. Woodward on the British Fossil 
Crustacea, we have a similar Catalogue of the fossil Foraminifera 
in the British Museum, printed also by order of the Trustees. 
This Catalogue having been prepared by Prof. T. R. Jones, one of 
our best authorities on this group of organisms, is a guarantee that 
it will form a useful work of reference to those interested in the Fora- 
minifera, or assist them in consulting the specimens contained in 
the national collection. In the introduction a general sketch is 
given of the nature and mode of growth of the Foraminifera, inclu- 
ding the differential character of the structure of their shells, upon 
which they are primarily divided into Imperforata or Porcellanea, 
and Perforata or Hyalina, and the former further subdivided into 
Calcarea and Arenacea, while some may have had limp, tough tests, 
consisting of material analogous to chitine, as Ceratestina. For so 
little is known of any real differentiation of the sarcode that 
there remain but few features of essential value for the classification 
of this infinitely variable order: “there are only the tissue, form, 
and structural peculiarities of the shell for determination; and 
these present many gradational phases, not only among individuals 
of any related group, but between the great groups themselves.” 
