316 



FSYCHE. 



[March, igoz 



coming wet. When the snow is melting so 

 as to prodyce small rivulets coursing along 

 the tracks of tlie luuibtrman's sleigh, these 

 snow-fleas are often observed, floating pas- 

 sively in its current, in such numbers as to 

 form continuous strings; whilst the eddies 

 and still pools gather them in such mvriads 

 as to wholly hide the element beneath them. 



Fitch's types of CoUembola are not 

 known to exist, so Dr. Felt wrote me. 

 Fitch's manuscript notes on tiie oi;der, 

 which belong to the Boston Society of 

 Natural History, I have read and copied, 

 thanks to Mr. Samuel Henshaw ; they 

 correct the original description thus: 

 "The antennae and legs are the same 

 color as the body, not reddish or deep 

 brown." ( Fitch appears to have had 

 Podura aquatica in mind, in the first 

 instance.) He adds, "In the early 

 spring the buckets and troughs of the 

 manufacturer of maple sugar are often 

 thronged witli these insects." 



Although the description of Podura 

 nivicola is less specific than is desirable, 

 and has consequently been the source 

 of some confusion, — nevertheless, the 

 evidence which I have collected leaves 

 no reasonable doubt in my mind, as to 

 the identity of Fitch's species. 



Three species (here called nifiio/a, 

 harveyi, and packarJi) have been and 

 may be confused, on account of their 

 superficial agreement in form and color, 

 — and only three have any claim to the 

 name of nivicola. These three are not 

 only sharply separated by structural de- 

 tails, but are also so different in time of 

 appearance, abundance, habitat, and 

 habits that they can be determined in 



the field. The form that I have re- 

 described as nivicola is the only one 

 that agrees with the original description 

 in being abundant at any time during 

 the winter, — and it may he. depended 

 upon to occur in immense numbers every 

 year, in the manner described by Fitch. 

 Harveyi seldom appears before the first 

 of March, in Massachusetts, where it 

 ■occurs on the trunks of pine and other 

 trees in but moderate numbers. I have 

 it as a " snow-flea" from Maryland, but 

 have never been able to find it as such 

 in Massachusetts, Maine, or New York. 

 Specimens collected for me in a sugar 

 camp in Maine, for the purpose of this 

 discussion,, proved to be what I had 

 called nivicola. Finally, Mr. MacGilli- 

 vray, in response to my request, sent me 

 " snow-fleas " from Osceola, Penn., and 

 Otto, N. Y., saying, " The one from Otto, 

 N. Y., is the common New York species." 

 Both lots consisted of the species that I 

 had already regarded as the real nivicola. 

 Packard's redescription of nivicola, 

 which subsequent writers have substi- 

 tuted for Fitch's diagnosis, cannot apply 

 to the nivicola established above, on ac- 

 count of the disagreement as to mucrones 

 and anal spines; moreover, nivicola has 

 disappeared from Salem and vicinity by 

 May 7, at the latest, — while Packard 

 gives May 28 and June 6 as two of his 

 three dates. It does not apply to 

 harveyi, for that does not occur much 

 after April 12, except in the egg. Only 

 one species remains to which it might, 

 and does, apply. Packard's specimens 

 of nivicola are lost, unfortunately, but 



