Reviews—Hall and Olarke—Paleozoic Brachiopoda. 133 
respects the more highly organised of the Inarticulata do approach 
the Articulata. To consider only one character, the formation of a 
hinge : in Barroisella, a descendant of Lingula, the deltidial callosities 
are developed to such a degree as to indicate their specialization for 
purposes of articulation; in Spondylobolus a similar result appears 
to have been arrived at by way of Obolella. Trimerella and Mono- 
merella similarly tend to develop articular processes in their pedicle- 
valve, while Neobolus has a strong cardinal process in its branchial 
valve. It does not, however, appear that as yet any distinct 
connection can be established between articulate and inarticulate 
genera. 
Another structure arrived at along two distinct lines is the plat- 
form of the so-called Trimerellide, a family that, if the authors’ 
conclusions are correct, can of course no longer be maintained. 
This platform has been evolved by the raising of the anterior edges 
of the stereom at the bases of the central and lateral muscles, a 
raising which the authors suggest is due to displacement of, and 
pressure against, the liver; this has induced a thickening of the 
entire area of muscle-attachment, and the solid plate so formed has 
been gradually excavated and changed into a more or less vaulted 
platform. The authors show that this evolution has proceeded from 
Lingula through Lingulops and Lingulasma to Trimerella, and again 
from Obolus through Elkania to Dinobolus. It is remarkable that 
both these lines should have culminated at the close of the Silurian 
period, both in the Guelph Limestones of Canada and in the upper- 
most beds of Gotland; but we would ascribe this to the natural 
working of the laws of growth rather than to any specially favour- 
able conditions of the later Silurian sea. 
Into their further investigations we forbear to follow these 
authors; this, however, is the less to be deplored, since a perusal 
of their work is not only absolutely necessary for the student of the 
Brachiopoda, but should prove both pleasant and instructive to all 
naturalists. For the book is written in a clear and interesting 
manner,—not too greatly marred by such phrases as ‘“‘a series 
eventuates,” ‘the edentulous brachiopods,” “features approach 
desuetude” and “to fortify a view,” and entirely free from the 
horrible jargon of ‘“naepionic,” “clinologic,” ‘“ephebolic” and the 
rest, that renders almost unintelligible some of the most valuable 
and suggestive American work; and there are besides 43 plates 
filled with figures most appropriately selected by the authors and 
admirably rendered by the artists. 
The large list of those in the United States, Canada, and the 
different countries of Europe, to whom Prof, Hall acknowledges 
his indebtedness, is a pleasing instance of that ‘‘federation of the 
world” in which scientific men are far ahead of politicians; and 
the bibliographic tables supplied by Mr. Charles Schuchert show 
that, at least to students of the Brachiopoda, the walls of Babel 
prove no hindrance. 
; F, A. BATHER. 
