HOMOGANGLIATA. 



Invertebrated Animals. 



No. 20. 

 TEGENEKIA MEDICINALIS. 



SPIDER, HOUSE-SPIDER. 



Tela aranece. 



The animal substance. A medicinal agent. 



Cobweb. Spider's web. 



Geog. Position. Europe, America. 



Quality. Sedative. 



Power. Febrifuge, antispasmodic. 



Use. Intermittents, spasmodic and nervous diseases. 



SCIENTIFIC ANALYSIS. 



Natural Classification. 

 3. DIVISION Homogangliata. CLASS Arachnida. 



Henz. Journ. Acad. Nat. Sci. II. 53. Jones, An. King. 308. U. S. Disp. 1316. 

 Wyatt, Nat. Hist. 118. EC. Disp. U. S. 398. 



GENUS TEGENERIA. 



Toile d'araignee (Fr.). 



THE ESSENTIAL CHARACTERS. 



Skin like bark, but neither horny nor calcareous. 



Head and thorax coalesce, leaving only two divisions of the 

 body recognizable externally, viz. the cephalo-thorax and 

 the abdomen. 



Eyes invariably smooth, from two to twelve, grouped in vari- 

 ous ways, never composite. 



Abdomen distinct, short, and globular, and furnished near its 

 posterior termination with spinnerets, by means of which 

 is constructed what is usually named the spider's web. 



Feet generally four pair, inserted at the thorax, and terminated 

 by two, sometimes three hooks. 



Respiration by pulmonary sacs, placed under the abdomen, or 

 by ramified tracheae, communicating with the external air 

 by fissures or apertures called stigmata or spiracula ; there 

 are from two to eight of them. 



Blood white, circulation in accordance with the mode of res- 

 piration. 



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