COLLEMBOLA OF THE FAMILY ISOTOMIDAE 109 



simple sensory setae. There are usually 4 long setae on the fourth 

 and on the fifth abdominal segment, and 8 or 10 on the sixth; 1 or 2 

 long lateral setae on the mesothorax and metathorax, respectively, 

 and one such seta on each of the first three abdominal segments. 

 Length, 1.8 mm (3 mm. Renter). 



Remarks. — At the time of maldng the original description of 

 macnamarai I had not found the postantennal organs, owing to their 

 unusual position. 



For a full figure of tliis species see Folsom, 1918. 



In view of Axelson's revision of the description of grandiceps 

 Renter, I regard macnamarai Folsom as synonymous with that species. 



According to Charles Macnamara, "This species seems to be con- 

 fined to wooded swamps; I have never seen it elsewhere; and it some- 

 times comes out on the snow in small numbers. This is the only 

 pugnacious springtail I have ever observed. It almost always attacks 

 an Achorutes put in the same vial with it and sometimes kiUs it." 

 The specimens from Ilhnois were taken in the frozen leaf stratum, 

 under snow. 



Distribution. — European writers have recorded this species from 

 Russia, Siberia, and Alaska. 



Massachusetts. Framingham, C. A. Frost (according to Mr. Macnamara). 

 Illinois: Urbana, February 2, I. H. Blake. 

 Alaska: St. Lawrence Island, Vega Expedition. 



Canada: Arnprior, Ontario, December 5, 7, 21, January S, 15, 26, February, 

 March 21, April, C. Macnamara. 



ISOTOMA (ISOTOMA) VIRIDIS Bourlet 



