THE HEDGEHOG OR URCHIN 57 



at zygoma, 34 to 36; posterior breadth, 31; breadth between orbits, 

 17 to 18 ; breadth at constriction, 14 to 15. 



Weight:— The Hedgehog, being a hibernating animal, probably 

 varies considerably in weight at different seasons of the year, being 

 theoretically heaviest just before and lightest some time during hiberna- 

 tion. Although this is probably true, there are no detailed supporting 

 observations. Webb's results {Zoologist, 1876, 4824-4825) were vitiated 

 by the fact that the Irish pair which he weighed at weekly intervals 

 throughout the year lived in the partial confinement of a garden, 

 and were fed on bread and milk in winter. He found that the 

 male was nearly always heavier than the female, especially in May 

 and June; he reached his maximum of 2 lbs. 7 oz. in the third 

 week of May, and dropped to his lightest in December and January 

 (i lb. 7-5 oz. to I lb. 8-5 oz.). The female seemed to follow a different 

 cycle, since, although also lightest in December and January (i lb. 

 6 oz. to I lb. 7-5 oz.), the heaviest weight she reached (i lb. 15-5 oz.) 

 was in the last week of October, in which week and the previous one, 

 she — for the sole time in the year — was slightly heavier than the 

 male. It would be interesting to correlate the variation in weight 

 with the accumulation of fat, supposed to be greatest in autumn 

 just before hibernation, at which time Webb's male specimen was 

 steadily losing weight. The extremes of weight, running from i lb. 6 oz. 

 to I lb. 15-5 oz. in the female, and from i lb. 7-5 oz. to 2 lbs. 7 oz. 

 in the male, agree with such isolated records as I have been able to 

 inspect ; but the experiment needs confirmation with wild animals, 

 great care being taken that the results should not be upset by irregular 

 feeding. 



Wadham writes me that he examined a very large Isle of Wight 

 specimen ; the weight was 3 lbs. 8 oz., so that it appears to have been 

 an exceptionally heavy animal. 



Although at first sight deprived by its structure of all means 

 of attacking its enemies, of defending itself by force, or of seek- 

 ing safety in flight, this animal is yet endowed with a tolerably 

 effective safeguard in its close covering of sharp spines. These 

 being hard without being brittle, sufficiently elastic to bear 

 great violence without breaking, and fixed with astonishing 

 firmness in the tough leathery skin, form not only a solid 

 shield-like protection from the effect of blows or falls, but a 

 shirt of prickly mail sufficiently sharp and annoying to deter 

 all but the most resolute of dogs from venturing an attack. 

 The moment a hedgehog is touched, or perceives danger 

 approaching, it rolls itself up into a compact round ball, by the 



VOL. II. E 



