G36 PROCEEDINGS OF WASHINGTON MEETING. 



The next paper also was read by title : 



GEOLOGICAL AGE OF THE SAGANAGA SYENITE. 

 BY H. V. WINCHELL. 



It is published in the American Journal of Science, 3d series, volume 

 XLI, 1891, pages 386-390. 



The following paper was read by title : 



THE RAILROADS AND THE GEOLOGY CLASSES IN ALABAMA. 

 BY E. A. SMITH. 



The following abstract represents a communication presented by title : 



ON THE FAMILY ORTHID^ OF THE BRACHIOPODA. 

 BY JAMES HALL. 



{Ahstract.) 



In thn paper the author has carried out the revision of the genus Orthis as begun in 

 the preceding volume of the Bulletin of the Society (page 19), making some farther 

 subdivisions, which are founded on important characters, and recognizing in all, in- 

 cluding the subdivisions of other authors and himself, fourteen distinct genera or sub- 

 genera, each one characterized by a number of well marked and, for the most part, 

 well known species of the genus Orthis as recognized in its broadest acceptation by 

 authors generally. It has long been recognized that this genus embraced heteroge- 

 neous material, and several generic names have been proposed and accepted as appli- 

 cable to certain groups of species. The very great number of species -which are cur- 

 rently referred to the genus Orthis, and the constant reference of new species, of varied 

 character, to the same generic term are sufficient evidence of a want of homogeneity 

 in the group ; and it has for a long time been the object of the writer to present some 

 scheme for the basis of a classification resting primarily upon the internal characters, 

 and also considering the relations of the external form, surface markings, and minute 

 shell structure, to the more vital manifestations. 



The paper presented at the Toronto meeting was a'preliminary attempt toward the 

 accomplishment of this object, but the record of the work up to that date had not 

 been fully incorporated. The studies since that time have enabled the writer to give 

 a more definite limitation to some of the groups and to recognize the necessity of a 

 farther subdivision in others. Under each group a generic or subgeneric term has 

 been proposed. These terms will not only be found useful to the student in arrang- 

 ing and classifying his collections, but will serve to give him some knowledge of 

 their geological range. The commencement and continuance of each generic group 

 in geological time will be indicated in the text and illustrated by a diagrammatic 

 arrangement under the geological series. A list of the known and verified species 

 will be given under each subdivision of the family. 



