TERTIARY SPIDERS AND OPILIONIDS 

 OF NORTH AMERICA 



INTRODUCTION 



The present study is based on collections placed at the disposal 

 of the author through the courtesy of the iSIuseum of Compara- 

 tive Zoology of Harvard University, of the U. S. National 

 Museum, of the American Museum of Natural History, of Pro- 

 fessor W. H. Twenhofel of the University of Kansas and of 

 Professor T. D. A. Cockerell of the University of Colorado. To 

 the above institutions and gentlemen the author expresses his 

 deep appreciation of the privilege thus accorded him not only to 

 reinvestigate the types previously descrilied by Scudder, but to 

 add several new species to those already known. The author is 

 also deeply indebted to Professor Charles Schuchert who was 

 instrumental in obtaining most of the material above mentioned. 

 Although the study of the specimens was completed some time 

 ago the work was considerably retarded at first by extraneous 

 activities of the author during the war time and later by the 

 difficulty of getting the proper help in making the drawings. All 

 attempts to photograph the material proved highly unsatisfactory. 

 Only a few specimens come out sufficiently well to allow of 

 reproduction. The majority of the specimens are so faint and 

 their colour so much like that of the surrounding rock that no 

 combination of rayfilters, plates and illumination systems is of 

 help in differentiating the specimens from the rock. At the same 

 time the specimens are sufficiently well preserved to be clearly 

 seen, measured and drawn. Thus drawings proved in every 

 way much more satisfactory than photographs and were prepared 

 by Miss F. E. Lovett. Mr. H. D. Rhynedance and myself. The 

 pictures given by Scudder on Plate XI of his stately volume on 

 Tertiary Insects of North America are so good that the expense 

 of redrawing them would not have been justified and the reader 

 is referred to Scudder's work. 



The collections above mentioned contain altogether two distinct 

 and hitherto unknown species of Opilionids and forty-seven dis- 

 tinct species of spiders representing seventy-six specimens or 89 

 pieces since several specimens consist of two pieces each. Six- 



