COLLEMBOLA OF THE FAMILY ISOTOMIDAE 83 



J. M. Brown sent me specimens of the species from England. 

 The specimens that I sent to Schiiffer I had compared with, and 

 found to agree with, a type of lateraria MacGillivray in the Museum 

 of Comparative Zoology. 



/. unica MacGillivray, of which I exammed one cotype in the 

 same museum, was evidently described from young individuals of 

 cinerea (about 1 mm in length), in which the antennae were short 

 and the claws as yet without teeth. 



7. dilatata MacGillivray agrees with cinerea Nicolet. In tlie single 

 type of dilatata in the museum at Cambridge, the tootli of the unguic- 

 ulus is wanting and the small lateral tooth of the macro is absent. 

 7. inclinata MacGillivray is also a synonym of cinerea, as 1 found 

 from three cotypes in the Museum of Comparative Zoology, and 

 two others given to me by A. P. Morse. In inclinata also the lateral 

 tooth of the mucro is absent. 



This species, one of our commonest collembolans, is found in 

 colonies, chiefly under the loose damp bark of trees or logs, but 

 occurs also on damp soil under sticks or dead leaves, and in moss, 

 I have taken it on oak, apple, willow, elm, cherr^^, maple, and syca- 

 more, and it doubtless occurs on other kinds of trees as well; once 

 I found it on a fungus. 



Distribution. — Isotoma cinerea is abundant in almost all parts of 

 Europe and has been recorded from Siberia and Franz Josef Land 

 also. 



Maine: Orono, July 20, October, F. L. Harvey. 



Massachusetts: Vicinity of Boston (Cambridge, Arlington, Lexington), Janu- 

 ary 16, March 20, April 12, 13, 17, 22, 23, May 7, 11, 13, 14, June 11. 

 Dover, Beverly, A. P. Morse (Museum of Comparative Zoology). 

 New York: Albany, May 7, D. B. Young (New York State Museum). Ithaca, 

 A. D. MacGilhvray (Cornell University). Macedon, April 0, 13, 20, 

 May 4, J. D. Hood. 

 Ohio: Sahneville, A. D. MacGilhvray (Museum of Comparative Zoology). 



Yellow Springs, February 4, 9, April 3. 

 Illinois: Homer, February 28, March 15, 31, April 2, 6, 9, 10, 12, 13, 10, 24, 

 25, May 12. Makanda, March 5, T. H. Prison and H. H. Ross (lUinois 

 State Natural History Survey). Oakwood, February 11, April 20, T. H. 

 Prison (Illinois State Natural History Survey). St. Joseph, February 

 11, H. H. Ross (Ilhnois State Natural History Survey). Urbana, February 

 13, March 11, 13, April 5, 11, 12, 14, 18, May 1, December. 

 Canada: Arnprior, Ontario, April, May 11, November, C. Macnamara. De 

 Grassi Point, Ontario, September, E. M. Walker. 



ISOTOMA (VERTAGOPUS) ARBOREA (Linnaeus) 



Plate 28, Figures 309-315 



Podura arhorea Linnaeus, 1758, p. 609. 



Isoloma arborea Bourlet, 1839, p. 402; 1841-2, p. 115.— Agren, 1903, p. 140.— 



Wahlgren, 1906b, p. 257. — Bartholin, 1916, p. 169. — Siioebotiiam, 1917, 



p. 221.— Brown, 1918, p. 186. 

 Isotoma reuteri Schott, 1894, p. 71; 1902, p. 23. — von Dalla Torre, 1895, p. 10. 



