Geology and Mineralogy. 71 



work either to a separate organization, or to the individual States 

 to be benefited thereby, would relieve the survey from both 

 criticism and expense. 



The paleontological work of the Survey has been done on a scale 

 which has excited the admiration of the scientific world. When 

 we consider the marvelous revelations which American paleon- 

 tology has made in the past few years any undue expenditure in 

 this direction may be charged to the lavishness of our rocks in 

 paleontological wonders rather than to any wastefulness on the 

 part of the survey. Paleontology is the basis of all interpretation 

 and classification of the geology of stratified rocks, and we hope 

 that the selection of one of our ablest paleontologists to be Director 

 will result in the application of the thorough methods of research, 

 used by Mr. Walcott in his interpretation of the Cambrian, to 

 all the departments of the United States Geological Survey. 



h. s. w. 



2. An Introduction to the Study of the Brachiopoda, intended 

 as a Handbook for the Use of Students. By James Hall, 

 assisted by John M. Clarke. (Report of State Geologist of 

 N. T. for 1891.) Pp. 135-300, plates 1-22, 1894. 



It is seldom that the authors of special monographs devote 

 their time and knowledge to the preparation of a general ele- 

 mentary work which will enable the student to gain a compie- 

 hensive view of a given subject. The Brachiopods are an 

 especially favored class of animals. Davidson, in 1851, published 

 his well-known and able "Introduction," which showed what 

 might be expected when the recent and fossil forms had been 

 more thoroughly studied. GUhlert, later, in 1887, prepared the 

 section relating to Brachiopods for Fischer's "Manual de Conchy- 

 liologie." It has been considered the best modern treatise on the 

 class, and is in every way an admirable resume. Zittel has also 

 given an excellent review of the group in his " Handbuch der 

 Pah"eontologie." 



The authors of the present work are especially fitted for the 

 task through their Ions; and intimate investigation of the Genera 

 of Palaeozoic Brachiopoda (vol. viii, Paleontology of New York), 

 and it is safe to assume that this handbook embodies a more 

 critical knowledge of the class than it has hitherto received in 

 similar elementary works. 



The introductory portion treats of the leading characters of the 

 Brachiopoda, together with their geographic and bathymetric dis- 

 tribution. The features of the shell are then discussed, with the 

 variations in form, ornamentation, and the special characters of 

 the cardinal area and delthyrium. The internal configuration of 

 the valves receives considerable attention, and includes features 

 of the articulating apophyses, muscular scars, pallial sinus, genital 

 markings, and structure of the test. The portion relating to the 

 animal itself gives a summary of the structure of the mantle and 

 pedicle, the muscular, alimentary, neural, and reproductive sys- 

 tems, and the numerous modifications of the brachia in various 



