98 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8 = 



Besides these direct means of defense, ticks and spiders exhibit in 

 a high state of development that class of protective adaptations known 

 as ciyptic coloration (both defensive and aggressive). Certain groups, 

 however, are brilliantly colored ; some spiders also have the body 

 integuments hardened and produced in the form of angles or spines, 

 and numerous spiders resemble ants. Among the forms of this class 

 ordinarily coming to the attention of man, spiders are by far the most 

 numerous, but the small often minute mites prove, when the care 

 necessary to their study is bestowed, to be exceedingly abundant. 

 However, these small forms are beneath the notice of most birds. 



The f ollowmg table shows the relation of the records of the various 

 orders to their approximate representation by species in the nearctic 

 region. 



Identifications of Arachnida 



Number of 



Order identifications 



Unidentified 26 



Xiphosura 20 



Microthelyphonida 



Scorpionida 18 



Pseudoscorpionida 80 



Pedipalpida 4 



Solpugida 24 



Phalangida 478 



Araneida 9,966 



Acarina 258 



Pycnogonida 11 



Percentage of 



identifications 



among those 



of all 



Arachnida 



.2386 

 .1836 



.1652 



•7343 

 .0367 

 .2203 



4.3873 



91.4729 



2.3681 



Percentage 

 of species 



in this order 

 among all 

 nearctic 



Arachnida ^ 



.0513 



•0513 



I.180I 



2.4II5 



.3078 



.6157 



34376 



66.7044 



23.0886 



2.1549 



Bird enemies. — Birds certainly specialize upon the group of arach- 

 nids — spiders — that to man seems most abundant and easily available, 

 over 91 per cent of their arachnid captures coming from this order. 

 We have records of more than 300 species of nearctic birds feeding 

 on spiders. The freedom with which they take these creatures is 

 illustrated by the following citations of records ; of those identified 

 to the order alone or about 92 per cent of the total, 81 birds have 

 from 10 to 49 captures each; 28 birds from 50 to 99; 15 from 100 



' Computed from Comstock, J. H., The spider book, etc., 721 pp., 1912, with 

 numbers of Araneida and Acarina approximated from the following works, 

 respectively: Banks, N., Catalogue of nearctic spiders, U. S. Nat. Mus. Bull. 

 72, 80 pp., 1910, and Banks, N., A catalogue of the Acarina, or mites, of the 

 United States, Proc. U. S. Nat. Mus., vol. 32, pp. 595-625, 1907. 



