PULMONARI^E. 30t 



moveable and usually soft abdomen; it is always furnished with from four to' 

 six closely approximated cylindrical or conical, articulated mamillae with 

 fleshy extremities, which are perforated with numberless small orifices for the 

 passage of silky filaments of extreme tenuity proceeding from internal reser- 

 voirs. Their legs, identical as to form, but of different sizes, are composed of 

 seven joints, of which the two first form the hip, the third the thigh, the fourth 

 and fifth the tibia, and the two others the tarsus : the last is terminated by two 

 hooks usually pectinated, and in several by one more, which is smaller and not 

 dentated. The intestinal canal is straight, consisting of a first stomach, com- 

 posed of several sacs, and then of a second stomach or dilatation surrounded 

 with silk. 



The nervous system is composed of a double cord occupying the median 

 line of the body, and of ganglions which distribute nerves to the various 

 organs. 



With respect to the simple eyes, or ocelli, M. Dufour remarks that they 

 shine in darkness like those of cats, and that the Araneides most probably 

 enjoy the faculty both of nocturnal and diurnal vision. 



The abdomen becomes so putrid and decomposed after death, that its 

 colours and even its form are soon destroyed. M. Dufour, by means of a 

 rapid desiccation, the mode of which he points out, has succeeded in remedying 

 this evil to a great degree. 



The silk, according to Reaumur, is first elaborated in two little reservoirs, 

 shaped like tears of glass, placed obliquely, one on each side, at the base of six 

 other reservoirs, resembling intestines, situated close to each other, flexed six 

 or seven times, proceeding from a little beneath the origin of the abdomen, and 

 terminating in the papillae by a very slender thread. It is in these last 

 mentioned vessels that the silk acquires a greater degree of firmness and other 

 properties peculiar to it; they communicate with the preceding ones by 

 branches, forming a number of geniculate turns, and then various pieces of 

 net-work. The newly spun filaments, when first drawn from the mamilla?, 

 are adhesive, and a certain degree of desiccation or evaporation is required to 

 fit them for their destined purposes. When the temperature is propitious, 

 however, a single instant is sufficient, as the animal employs them the moment 

 they escape from the apparatus. Those white and silky flocculi that may be 

 observed floating about in spring and autumn in foggy weather, are certainly 

 produced as we satisfactorily ascertained by tracing them to their point of 

 origin by various young Araneides ; they are mostly the larger threads which 

 are intended to afford points of attachment to the radii of the web, or those 

 that compose the chain, and which, becoming more ponderous by the access 

 of moisture, sink, approach one another, and finally form little pellets: we 

 frequently observe them collected near the web commenced by the spider, 

 and in which it resides. 



It is also very probable that many of the young animals, not having as yet 

 a sufficient supply of silk, limit their structure to throwing out simple threads. 

 It is, I think, to the young Lycosae that we must attribute those which inter- 

 sect the furrows of ploughed grounds, whose numbers are rendered so apparent 



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