REVIEWS 759 
published, and dwell with laudable earnestness upon the confusion 
resulting from carelessness and from opinions based upon inadequate 
investigation. ‘The great variability of the Os¢ezd@ is emphasized, but 
the authors correct the opinion previously held that this variability 
destroys their value in stratigraphy. They show that the hemere of 
many forms have well defined limits and are, therefore, of the greatest 
use in determining horizons. No classification yet given is satisfactory 
for the Texas Ostrerde. ‘The forms are tabulated provisionally under 
the old familiar names. 
After this discussion, which deals in some measure with the family 
in general, the authors confine their attention to the specific object of 
the paper. The various forms which have been referred to Gryphea 
ditchert are discussed from a historical standpoint and their strati- 
graphic and geographic distribution noted. The species of the group 
are specifically defined and many data given regarding their develop- 
ment and methods of growth, and lastly, something of their phylogeny. 
A large part of the bulletin is taken up with plates showing the various 
species at different stages of growth and the individual shells in differ- 
ent positions. ‘The figures formerly published are also reproduced for 
comparison. ‘The work is especially commendable for careful investi- 
gation and clear-cut presentation. Wot ine, 
Le Grant des Pyrénées et ses phénoménes de contact— Premier 
memow.: Les contacts de la Haute-Ariége, par M. A. 
Lacroix, Professeur de Minéralogie au Mus. d’Hist. Nat. 
Bull. des serv. de la carte géol. de la France. No. 64, tome 
Xe atic oOo: 
The area which has furnished the results published by M. Lacroix 
in this bulletin is situated in the very mountainous southern tract of 
the Departement of the Ariége, about roo southeast by south of the 
city of Toulouse. The Ariége, one of the head waters of the Garonne, 
flows through the region. Most emphasis is laid on the phenomena of 
contact exhibited on the right bank of the stream, since the exposures 
are considerably more accessible and continuous than on the left bank. 
The facts of observation on both banks are, however, accordant. 
This, the first memoir on the granite massifs of the Pyrénées, is 
devoted to a purely mineralogical treatment of igneous contacts, which 
