788 THE POPULAR SCIENCE MONTHLY. 



ciently designated wlieii it is named. In these animals the head 

 and corselet are confounded into a single mass, at the upper part 

 of which is a kind of dorsal buckler, supporting in front the or- 

 gans of vision. The eyes are generally eight in number, but are 

 variously grouped, according to the types. Walckenaer, at the 

 beginning of this century, made the disposition of the eyes a cri- 

 terion of distinction between the genera and species. More re- 

 cently, some remarkable coincidences having been noticed be- 

 tween the disposition of the eyes and the habits of the species, it 

 became recognized that that feature could be relied upon in an 

 animal wholly a stranger to determine the conditions of its exist- 

 ence and the way it got its living. The eyes do not turn in 

 their socket like man's, for the cornea is only a tegumentary part 

 which remains transparent. This immobility is an imperfection 

 which is amply compensated for by the different orientations of 

 the numerous organs, and their dispersion and grouping in such 

 a manner as to respond to all the visual necessities of the ani- 

 mal. Being silent animals, and never having to answer to a 

 call, spiders are backward in distinguishing sounds. This fact is 

 assured by some features in their conformation. The romances 

 that have been woven about their fondness for music are purely 

 illusory. The disturbances which they experience at the playing 

 of violins and pianos are simply effects of the vibration of their 

 webs. Alarmed by it, they quit their hiding-places and rim 

 about in panic. 



Beneath the front of the spider project two thick processes 

 armed with a movable hook — the antennae forceps — which con- 

 ceal a poison-gland with a little tube running out to near the 

 point of the hook. All who have seen a spider taking a fly have 

 remarked how it stings its victim so as to kill it before introduc- 

 ing it to its mouth. At the edge of the buccal orifice of those 

 species that live on fluids, exist only a simple tongue and two 

 highly developed palpi behind it. 



Spiders are differentiated from insects, which have six legs, by 

 having four pairs of legs (Fig. 1). These members support hooks 

 at their ends, which are working instruments of astonishing per- 

 fection. The body and limbs are covered with hair, fine down, 

 and spines. These are the organs of touch, often of exquisite 

 sensitiveness, planted in the skin. Under the microscope the downy 

 hairs, which are hardly visible to the naked eye, appear fringed 

 and bearded like incomparably delicate feathers. When we con- 

 sider the habitual neatness of their clothing, to which grains of 

 dust would so readily stick, we are satisfied that spiders are far 

 from the hindmost in the care they give to their toilet. Their long, 

 hooked legs perform an office that leaves nothing to be desired. 

 At the extremity of the body may be found mobile articulated 



