352 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



eisht changes for the first twelve months of the life of the 

 finimal. During the second year there are five moults, and 

 in the third year generally two, and sometimes three. The 

 male craw-fish is mature from the commencement of the third 

 year, the female at the end of the fourth. At this age the 

 latter has only one moult per annum ; the male, on the con- 

 trary, has two, which may explain the larger size, since the 

 growth is in proportion to the number of these changes of 

 skin. It usually requires forty-eight hours for the new skin 

 on the back of the crab to arrive at a sufiicient degree of per- 

 sistence, although the legs become completely hardened in 

 twenty- four hours. Jour. Acad. Nation. Agric, etc.^ Feb- 

 ruary and March^ 1873, 99. 



HIBEKNATION OF FLIES. 



An interesting statement is presented by Goubareff upon 

 the hibernation of flies, subjected to alternations of heat and 

 of excessive cold in Russia, as taking place in the Russian 

 establishments used for the production of vapor-baths, which 

 are kept heated only on the days when the bath is to be ap- 

 plied. One or two of these had been heated only twice in 

 six months on the 3d of January and 15th of February. 

 The thermometer in the open air indicated a temperature of 

 13 Fahr.,and one in the interior of theiouse stood at 14 

 Fahr. An immense number of flies had established them- 

 selves in this building from the month of August, and had 

 been sluggish since the month of October; but when the 

 house was heated up to 106 Fahr., they became as active 

 and lively as in the heat of summer, immediately returning 

 to their original torpor whenever the cold obtained the mas- 

 tery in the abandoned building. 6 B^ March 24, 1873, 785. 



FLIGHT OF THE ISTHMUS BUTTERFLY. 



According: to the Panama Star and Herald, the beautiful 

 Isthmus butterfly, Urania fulgens^ according to Salvin, and 

 not TJ. leilus^ as generally supposed, the immense migrations 

 of which from east to west excite so much attention every 

 year, continued abundant through the month of August, al- 

 though the problem as to the points where it begins and ends 

 its journeys is still unsolved. Panama Star and Herald, 

 August 24, 1873. 



