200 ENTOMOLOGICAL NE^^s. [December, 



A CONJECTURE. 



By Charles C. Cresson, Germantown, Phila. , Pa. 



In reading of the irnmense congregations of Butterflies, that 

 sometimes have been observed in the Fall of the year, it is an 

 interesting subject for reflection as to the Divine i?itention in en- 

 dowing them with the instinct of collecting together, and the 

 purpose intended to be carried out. This habit of immense con- 

 gregations is not confined to Butterflies, but is to be observed in 

 an unknown number of other animals. Our American Buffalo, 

 or Bison, collect in very large herds at a certain season of the 

 year, as Catlin relates, for the purpose of continuing the species; 

 and when so collected, the bulls forthwith commence to struggle 

 and fi^ht with each other, the stronger conquer the weaker ones, 

 and then choose such mates as please them. The large congre- 

 gation then separates into little family groups, each with its own 

 masculine head, and so enters on to the business of multiplication 

 and addition, and then remains in peace and quiet until the next 

 annual return of the season for reassembling — A clear and mani- 

 fest instance of the " Survival of the Fittest," the most powerful 

 bulls continuing the species, and many of the weak ones being 

 killed or disabled. The Wolves congregate in packs for mutual 

 assistance, then prowl around these herds and families, hunting 

 for something to devour; and when they find a stray Buffalo, too 

 much alone for its own good, they attack him, her, or it (the 

 calf), as the case may be, and breakfast, or dine, on their prey 

 (as described by Catlin). 



The Norwegian Lemming, as described m the ' ' Encyclopedia 

 Brittanica" and elsewhere, occasionally migrate in great numbers, 

 pursuing their course in a straight line, regardless of every ob- 

 stacle, and consuming everything eatable in their way (Baird). 

 Their usual course is from the East to the West; they swim over 

 rivers and lakes until they arrive at the Atlantic Ocean; then they 

 continue to follow their leaders, plunge together into the ocean 

 and swim out to sea; they never swim back again, but all are 

 drowned in the mighty waters. On their journey from their 

 home to the ocean (which lasts sometimes for over a year) they 

 procreate and largely increase the congregation. The young and 

 old keep straight on, and all perish in the company of each other. 



