l6 SMITHSONIAN INSTITUTION 



of the artist ; then the picture is worked out with India ink under a low power 

 magnifier, every part being carefully gone over with the brush. Thus scien- 

 tific accuracy and artistic effect are combined. 



The adequate reproduction of the work of such artists is no simple matter, 

 and calls for a degree of care and skill far beyond that of the ordinary com- 

 mercial printing. It has been accomplished by the Heliotype Company of Bos- 

 ton in a manner that is worthy of the drawings. No pains have been spared to 

 insure the most perfect effects, and it is to the constant attention and vigilance 

 of the company's manager, Mr. W. C. Ramsay, that the admirable results are 

 especially due. 



Acknowledgments 



One other acknowledgment remains, not so easy to fittingly express, and 

 that is in relation to Mrs. Bernhardina Wachsmuth, widow of my old friend 

 and associate, Charles Wachsmuth. It is rendered doubly difficult by the fact 

 that the demise of this venerable woman, pending the publication of these lines, 

 compels me to substitute words of affectionate remembrance for those of grate- 

 ful recognition. After the death of Wachsmuth in 1896 I took over the collec- 

 tion and library which had been accumulated by us together, and thereafter 

 maintained them in the private museum which we had constructed) for their 

 security, until I transferred them to the National Museum in 191 1. During 

 that period of 15 years, although my residence and business affairs were in 

 New Mexico, I continued my scientific researches at such intervals as my time 

 and other occupations would permit in the little museum in the beautiful city 

 of Burlington, Iowa. The manifold kindnesses, the solicitude for my personal 

 comfort, and the intelligent interest in my work which were at all times ex- 

 hibited by Mrs. Wachsmuth, could not be adequately characterized by the 

 ordinary expressions of gratitude. 



But I wish to here record my appreciation of one of the finest characters I 

 have ever known. She was her husband's untiring companion and helpmeet 

 through all his long years of study and of battling for health, not only in a 

 material way, but intellectually. While without a technical knowledge of 

 geology and paleontology, she was always an intense lover of nature, and a 

 keen observer as well; so she became an ardent and skillful collector, and for 

 the last 20 years of his life accompanied Wachsmuth in all his travels and col- 

 lecting journeys, tramping cheerfully over mountains and searching among 

 glades and outcrops with an energy that never flagged. Many splendid speci- 

 mens that enrich this great collection were of her finding. She not only 

 rejoiced in their discovery with the zest of the successful collector, but appre- 

 hended their scientific importance as contributions to the problems that were 

 under investigation. The same intellectual interest was maintained toward 

 my own researches, manifested by sympathy and cooperation limited only by 



