288 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



transparent, and seem to have a pupil and iris ; the nocturnal are, on the 

 contrary, dull and opaque. 1 



Lebert expresses the same opinion, 2 adding further that those which are 

 most convex and brightly colored, serve to see during daylight, and the 

 others, which are flatter and colorless, serve during the dusk. It occurred 

 to me to test this theory by making such division on the basis of habit, 

 as above referred to, and observe whether the spiders which incline to 

 nocturnal habits have the nocturnal or white eyes, and vice versa. Such 

 a comparison, extended to a few species, shows the following results : 



Among our indigenous Orbweavers, those whose night habits are most 



pronounced, or whose ordinary habitat is dark or shaded places, proved to 



have light colored eyes. For example, I rarely find Epeira strix 



upon her web in daytime ; she comes out for prey in the early 



, . evening or twilight, and remains quite persistently throughout 

 Eyes ^ ne ^ ii y * n ner nes t ^ curled leaf or in some convenient den. 

 The eyes of this species have the entire rear row and the side 

 eyes of the. front row a light gray color. The middle front eyes are of the 

 same color, but a darker shade. Meta menardii, which persistently inhab- 

 its shaded places, and which I have found in caves in central Pennsylva- 

 nia, has all its eyes a light pearl or gray color. The specimens of this 

 species examined were found in Sinking Spring Cave quite distant from 

 the mouth. The Kay spider I have always found in ravines or well shaded 

 spots under the cover of ledges or foliage. Its eyes are all a light pearl, 

 the middle front eyes having a little darker shade. 



Turning to other tribes I found, for example, that the Medicinal spider 

 (Tegenaria medicinalis) has all its eyes yellow, with the exception of the 

 small midfront pair, which are dark with a marginal ring of light color. 

 Its dwelling place is habitually cellars and dark corners. I have often 

 found it living quite in the shade. 



Clubiona palens, which lives within a silken tube and is frequently 

 found underneath stones, has pearly white eyes, the middle front being a 

 slightly darker shade. The eyes of Agalena nsevia are all a uniform bril- 

 liant yellow (amber), rather darker than Tegenaria medicinalis. This spi- 

 der inhabits a tube which -expands into a sheeted web. She keeps habit- 

 ually on guai'd within the mouth of her tube, but sallies forth at all hours 

 of the day after the prey which drops or alights upon her web. She evi- 

 dently possesses good day sight. So far, therefore, one might say that the 

 conjecture that the white eyes are used for seeing in the dark, are nocturnal 

 eyes, in fact, is corroborated. 



But a further examination introduces facts which are in serious conflict 

 with the theory. For example, Argiope cophinaria lives persistently in the 



1 Simon, llistoin- Naturelle des Araignees, page 35. 



2 Die Spinnen der Schweiz, page G, quoted by Lubbook, "On Ants, Bees, and Wasps," 

 Linn. Soc. Jour., Vol. XX., 125. 



