330 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



being nearly always white, or a faint livid, or a delicate hue of pink or 



yellow. I do not know whether the absence of spines characterizes the 



young of those species that show these peculiarities in adult life. 



Abdom- jf. ma y k e ^at tj ie development of these thorn like processes is 



J? a . in some way connected with the development and growth of 



the young spider, and is only completed at maturity. It would 



be interesting to know the physiological causes of this vital phenomenon. 



Some of those species which have soft conical tubercles upon the fore 

 part of the abdomen show these very early in the young. I have observed 

 them distinctly formed upon at least two of the Angulata group of our 

 American Epeira, gemma and bicentennaria. In the case of Argiope coph- 

 inaria the spiderling immediately after escape from the egg (the first moult) 

 appears to be without the processes or bifurcations which mark the base 

 of the abdomen of that species, but after the next moult these show plainly. 

 (Compare Fig. 305 with Figs. 306 and 307.) 



When the young of Tegenaria medicinalis first break from the shell, 

 the legs and palps are white and semitransparent. The eyes stand out 

 brown and distinct upon the face. The cephalothorax in the 

 fore part has a slight bluish or lead colored tint, with a touch 

 of yellow at the posterior part near the abdomen. The mandibles are the 

 color of the cephalothorax, but with the fangs prominent, feeble looking, 

 whitish, instead of the dark, horny appearance of the adult. The abdo- 

 men is a uniform yellowish hue, at the apex of which the spinnerets ap- 

 pear lead colored, the long, jointed pair quite prominent. The spines are 

 quite manifest on the legs, and hairs are seen on the abdomen. The fo- 

 lium or dorsal figure can be traced, together with the transverse bars, on 

 either side of the median line. In a day or two the color of the legs 

 deepens until they have a leaden hue, upon which the black spines stand 

 out more prominently. The abdomen is a little brighter yellow, and the 

 cephalothorax corresponds in color with the legs. In two days more tin- 

 yellowish tint has faded from the abdomen, the whole spider has a black- 

 ish appearance, caused by the dark hairs upon the lead colored body ; the 

 transverse markings stand out more prominently upon the abdomen. 



The young of Epeira cucurbitina (English) when extracted from the 

 egg have the cephalothorax and legs of a pale yellowish white color, that 

 of the abdomen being reddish brown. But after their first change of in- 

 tegument they acquire an olive or brownish green tint, the upper part of 

 the abdomen being metallic with whitish spots on each side, with a longi- 

 tudinal stripe of the same hue parallel with it. On the upper side there 

 is a series of minute black spots. 1 These examples will be ample, when 

 compared with adult forms, to enable the student to note the color changes 

 that occur during the growth of spiders. 



1 Spiders of Great Britain and Ireland, page 343. 



