210 PREFACE. 



There has, of course, been no attempt to bring the Report down to 

 the present day. It represents our knowledge in respect to the subject- 

 matter as it was a dozen years ago, except where Dr. Torrey has him- 

 self introduced references or views of a later date, and except the 

 very few cases in which published names inevitably supersede those 

 imposed by the author and still in manuscript. Otherwise my work 

 has been almost wholly of a clerical kind, or has related to the cor- 

 rection of oversights, to typographical arrangement, &c. Whenever 

 an explanatory remark was thought needful it has been added. But 

 all such notes are inclosed within brackets. 



It is much to be regretted that this Report was not printed and pub- 

 lished, as was expected, in the year 1861, and that it did not receive 

 the final corrections which the lamented author would have given, if 

 he had himself lived to see it through the press. To do the best that 

 can be done with it under the actual circumstances has been the 

 endeavor and the sacred and sad duty of the present editor. 



ASA GEAY. 

 Washington, April 15, 1873. 



