The External Anatomy of Spiders 



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Fig. 74- 

 THE MODEL REPRESENTED 

 IN FIG. 73 VIEWED FROM IN 



FRONT; THE ANTERIOR 

 ROW OF EYES IS RECURVED 



is said to be procurved; when the lateral are farther back than the 

 median eyes the row is recurved. In determining whether a row 

 of eyes is procurved or recurved, a line passing through the centre 

 of the eyes is considered, and not one tangent to either anterior 



or posterior border of them, and in case 

 of the anterior row they should be viewed 

 from in front. In this case if the an- 

 terior lateral eyes are higher than the 

 anterior median — i. e., farther from 

 the edge of the clypeus — the row is 

 recurved, although when seen from 

 above the lateral eyes may be farther 

 forward than the median eyes and con- 

 sequently the row is apparently pro- 

 curved. This is illustrated by the 

 accompanying two views of a model 

 (Fig. 73 and Fig. 74). 



Sometimes the curvature is very 

 great, and the posterior median eyes are 

 widely separated; then the eyes are said 

 to be arranged in three rows (Fig. 75); 

 and in some cases the eyes are in four 

 rows, each pair of median 

 eyes and each pair of lateral 

 eyes constituting a row 

 (Fig. 76). 



The Areas of the 

 Head. — Special names are 

 applied to different areas of 

 the head; but the areas thus designated are not 

 limited by sutures and consequently the names 

 applied to them do not have the definite morpho- 

 logical significance that similar names have in de- 

 scriptions of insects. The areas most commonly 

 recognized are the following: 



The eye-space. — That part of the head which 



is between the rows of eyes is termed the eye-space. 



The median ocular area. — The space limited by 



the four median eyes and including that occupied 



by these eyes is termed the median ocular area. 



Fig. 75. 

 EYES IN THREE ROWS, 

 LYCOSA CAROLINENSIS 



Fig. 76. 

 EYES IN FOUR 

 ROWS, LYSSO- 



MANES 



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