OF LANCASTER COUNTY. 519 



CLASS AKACllNIDAi 

 To this class belong all those ammals commonly known under tlie name of "Snidcrs," 

 "Ticks," "Mites," "Fals-scoi]iions," etc., and which are generally (listinguislied from 

 Insects in having eight feet instead of six— hence they are also called " UcIoikkIs"— 

 and in having the head and the thorax united in one piece, called the cepluila thorax. 

 They are without antenme, and the legs are seven-jointed, terminating with the two- 

 jointed tarsi. At the base of their mandibles, or jaws, there are small vesicles filled 

 with poison, which can be poured into the tips of the jaws and thus poison any animal 

 that is bitten by the spider. Unless man, however, is in such a state of health as to 

 render his constitution open to the reception of injury from their bite, there is no spe- 

 cies of spider in the county of Lancaster that can do him much hami. Iklosfiuitocs 

 and horse-flies, under similar circumstances, are as capable of inflicting as serious inju- 

 ries upon the human species as are spiders. The young are produced from eggs, and 

 after they are hatched therefrom, they moult or cast oil" their skins a number of times 

 before they attain their perfect state. Spiders usually live upon animal food, and aro 

 most voracious feeders, and hence they may be regarded as friends to the human family. 

 There are some species, however, of this class, that live upon vegetable substances, 

 especially among the acaridae, but the larger number of even these are parasitic upon 

 the bodies of other animals, and especially upon those of insects. Spiders difler very 

 much in their habits, some spinning complex webs and others very simple ones. Some 

 construct their nest high up among shrubbery and trees, and others low down upon tho 

 ground, or under stones, or in cavities under the ground, whilst others spin no web at 

 all, but, like a tiger, lie in wait for their prey and suddenly pounce upon it. Some aro 

 aquatic in their habits, but the larger number of species are strictly tciTCstrial. Per- 

 haps there is no other class of animals, of the same size, that has elicitcfl so little sys- 

 tematic attention as that of spiders, and therefore a i-eliablc list of what even Lancaster 

 county contains, cannot be given at the present time. The Arachnids are diviflcd into 

 two primary groups, called Pulmonaria and Trachearia. 



PULMONARIA. Sphasus. 



-r, . nitidans 



Fam. Aranid^e. , . 



scalaris 



Mygale. Attus. ' 



Several species. insolens 



FiLiSTATA. familiaris 



hibernalis viridis 



Dysdera. niger 



teterrima rniw^ 



Segestria. sylvanus 



pumila vittatus 



Lycosa. castaneus 



fatifera •'*"'^ several other species 



ocreata Tiiomisus. 



littoralis vulgaris 



punctulata a»d othtr species, 



and other species. Clubioxa. 



DoLOMEDES. obesa 



tenebrosa gracilis 



sexpunctatus tranquila 



lanceolatus a'"^ others, 



and other species. IIerpyllcs. 



1 Contributed by Mr. S. S. Rnthvon. 



