WEAVER: INVERTEBRATE PALEONTOLOGY AND HISTORICAL GEOLOGY JQJ 



King (1846) in the construction of a classification in which the Brachiopods 

 were subdivided into 3 orders, 16 families, and 49 genera. The important mono- 

 graphs by Thomas Davidson published at intervals from 1851 to 1885 present 

 an excellent analysis of the morphological characters of the hard parts of both 

 fossil and living Brachiopods, along with a description of the soft parts by 

 Richard Owen. The classification is in part the one used at the present time and 

 was constructed with special attention to details of muscular scars, the hinge, the 

 shell material, and, in some forms, the brachial system. Other important con- 

 tributions during the past one hundred years have been made by J. Barrande 

 (1879) on the Silurian faunas of central Bohemia, Waagen (1879-1895) on forms 

 from the Salt Range in India, Rothpletz in 1886, James Hall, J. M. Clarke, C. E. 

 Beecher, H. S. Williams, E. R. Cumings, P. E. Raymond, C. D. Walcott, F. L. 

 Kitchin, Carl Diener, Charles Schuchert, G. A. Cooper, C. 0. Dunbar, Hertlein 

 and Grant, and numerous others. 



The majority of the larger monographs and papers contain descriptions of 

 new genera and species from particular areas or formations. Among these are 

 studies on the Guadalupian faunas by G. H. Girty (1908), the Cambrian brachio- 

 pods by Walcott (1912), those of the Kutch Jurassic in India by Kitchin 

 (1900), and the Tertiary forms by Sacco (1902). Other papers deal largely 

 with problems of morphology and phylogeny of special groups or of the class 

 as a whole. Important studies on the development and classification of stages 

 of growth of brachiopod shells were published in 1891 and 1892 by C. E. Beecher, 

 who applied the law of morphogenesis as earlier proposed by Hyatt. The prin- 

 cipal factors used were those of growth and acceleration of development, of me- 

 chanical genesis, and geological sequences of genera and species. Special at- 

 tention was devoted to the study of the embryonic shell or protegulum and its 

 modifications resulting from acceleration, thus showing how the nepionie and 

 neantologic characters are pushed forward and appear earlier in the history of 

 the individual so as to become impressed on the early embryonic shell. As a 

 result of special studies of the pedicle opening Beecher outlined the origin of 

 the deltidium and deltidial plates and developed a classification of stages of 

 growth and decline through the embryonic and larval stages. 



E. R. Cumings (1903) published a paper on the morphogenesis of the post- 

 embryonic stages of the genus Platystvophia in which he followed the principles 

 used by Hyatt, Beecher, and Jackson. This was a critical study of the nepionie, 

 neanic, ephebic, and gerontic stages of the genus with a general discussion of 

 the history of the genus and the laws governing its evolution. Two important 

 contributions, by Charles Schuchert and by Schuchert and Cooper, have added 

 greatly to the knowledge of the brachiopods. The first paper (Schuchert, 1897) 

 presents tables of species of North American brachiopods arranged by periods 

 and with a classification consisting of 4 orders, 49 families and subfamilies of 

 which 43 became differentiated in the Paleozoic and 30 were extinct before its 

 close. Thirteen continued into the Mesozoic and 6 are represented by living spe- 

 cies. The structural characters are given for each order and the classification 

 is built upon morphologic and phylogenetic principles. The second paper ( Schu- 

 chert and Cooper, 1932) is a detailed study of the suborders Orthoidea and 

 Pentameridae. The authors consider that the division Orthoidea contains the 

 primary stock from which all articulate brachiopods, including the order Telo- 



