SCIUROPTERUS VOLUCELLA. 20^ 



energy of tlunr movements at first, the)- usually increase in vi^or 

 antl speed until aftc;r mitlniolu and scarcel)' orow less before morn- 

 ing-. Xothino- aflords th(;m so much gratification as a large wheel 

 which is placed inside the cage. Into this wheel they jump when- 

 ever aught disturbs or pleases them, and even when cpiite hungry 

 the)- often find it necessary to take a few turns before commencing 

 their meal, after which exercise the)- draw themselves into a bunch 

 with the tail ox'c-r the back, after the manner of scpiirrels. ami set 

 briskl)- to work on tin; nut or other food they ma)' have 

 receixed. idle)- are almost as fond of riding as of running, and 

 work their passage b)- runnii-ig till the wh(>c;l is in rapid niotion and 

 tli'Mi clinging to its wires, and so are carric-d around and around, 

 the pure white of the under side of the bod)- contrasting prettil)' 

 with the sott brownish-gra)- ot the back and sides as each comes 

 into view. \\ hen both are in the wheel one often rides while; the 

 other turns the wheel, the latter bounding ovv.r the other as each 

 turn brings hini around, and, no i-nattcM' how rapidl)- the wheel 

 turns, these moxenients iwc executed with perfect exactness and 

 gracefulness. Being desirous of knowing with sonie degree of 

 accurac)- how rapidly the wIk^cI mo\-ed, 1 made some experiuKMits 

 for that purpose and found that the usual rate of revolution was 

 from sixt)- to over a hundred and twent)- times a niinute, and, as 

 the wheel is fort)--four inches in circumference, when its rate is the 

 latter of the two numbers named, the scpiirrel turning" it must 

 travel four hundred and fort)- feet a minute, or about live miles an 

 hour, a distance recpiiring a great many steps when they are 

 so short as s([uirrels niust take;. The sides of the wheels are formed 

 of spokes radiating as in an)- wheel, these spokes are onl)- h\'e 

 inches apart at the; circuniference and of cenirsc; constantly grow 

 less toward the centre ; )-et through this narrow space which i)asses, 

 when the wheel is at full speed, in the sixteenth of a second, they 

 dart ill and out with perfect ease. So (juickl)- do they move that 

 the eye can scarcely follow them ; one instant a squirrel is in the. 

 14 



