2 BULLETIN 168, UNITED STATES NATIONAL MUSEUM 



In addition, I collected in eastern Massachusetts, including Essex 

 County, most of the species that Packard described from that region, 

 and compared them with liis types. 



Of the MacGillivray (1896) cotypes and other specimens of Isotoma, 

 I have studied three sets: The collection of the Aluseum of Com- 

 parative Zoology; the collection of Cornell University, through the 

 courtesy of Prof. C. R. Crosby; and a set of specimens given to me by 

 Dr. MacGillivray. 



Guthrie's (1903) types and other material were kindly loaned to 

 me by Prof. H. F. Nachtrieb, and many additional specimens were 

 received from Dr. Guthrie. 



The entire collection of Prof. F. L. Harvey, with his notebooks, I 

 bought from Mrs. F. L. Harvey. 



The Apterygota of the California Academy of Sciences described 

 by Schott (1896a) were destroyed by fire, so I was informed by the 

 secretary of that institution. 



Important among large collections received for study were those of 

 the Illinois State Natural History Survey, through the courtesy of 

 C. A. Hart and Dr. T. H. Prison; the New York State Museum, 

 through S. C. Bishop and D. B. Young; the American Museum of 

 Natural History, through Dr. F. E. Lutz; and Stanford University, 

 through Prof. V. L. Kellogg. 



From California, collembolan material in abundance came from 

 the late Prof. C. F. Baker, Prof. E. O. Essig, and A. P. Morse. From 

 Oregon, a large collection was received from Dr. H. E. Ewing, and 

 from Florida one from Prof. T. H. Hubbell. From Iowa, specimens 

 in abundance were contributed by C. N. Ainslie, and from Tennessee 

 many by G, G. Ainslie. Much Pennsylvania material came from 

 Dr. H. A. Surface, and a great number of New York specimens from 

 Dr. M. D. Leonard, Prof. C. R. Crosby, Dr. H. Glasgow, Prof. J. D. 

 Hood, and E. A. Maynard. 



For Canadian species acknowledgments are due to Prof. E. M. 

 Walker, and especially to Charles Macnamara, who has for many 

 years been sending me a wealth of material. 



The greater part of the material used, however, I collected, chiefly 

 in Massachusetts, Ohio, Illinois, Wisconsin, and Louisiana. The 

 omission of a collector's name in the data concerning specimens means 

 that they were collected by me. Similarly, the omission of refer- 

 ences (in parentheses) to the ownership of specimens indicates that 

 they are in my collection. 



The illustrations, made by me, were drawn from type specimens 

 when possible. 



The most important part of the material studied has been given to 

 the United States National Museum. 



