NO. II LEGS OF PRIMITIVE ARTHROPODS EWING 5 



the number of segments in a solpugid leg is high, being seven or eight 

 in addition to the claws. 



In eight-segmented legs (pi. i, fig. i) there is a somewhat flat- 

 tened, short basal segment, then three short doubly-hinged cylindrical 

 segments, followed by three long segments and lastly by the terminal 

 claw-bearing segment, which has two or more false rings. According 

 to Bernard (1896) the basal segment represents the coxa, but others 

 have regarded this segment as a sternite. Bern^ard is inclined to follow 

 Gaubert in accounting for the extra segment in the eight-segmented 

 legs through a division of the femur. Yet in regard to this point he 

 remarks, " I am unable to judge, having never seen the animals alive." 

 S^rensen (1914) regards the first long segment (the fifth of an eight- 

 segmented leg) as the femur, which has been the customary practice. 



When the musculature and the movements of the third or fourth 

 leg (pi. I, fig. i) are studied, a very interesting and vuiusual condi- 

 tion is revealed. Each of all four of the basal short segments bears 

 the segment distal to it by means of a double hinge, and all of these 

 hinges work along a more or less vertical axis ; no two, however, are 

 in the same plane. The type of musculature for each of these seg- 

 ments is the same. There are two powerful muscles in each that arise 

 from the base of one segment and attach to the basal apodeme of the 

 next. One of these muscles moves the segment distal to it backward, 

 the other forward. The first and second long segments each has its 

 interior almost completely taken up by a powerful fiexor muscle 

 moving the segment distal to it. 



The writer has been unable to detect in the solpugid leg any muscle 

 in the first five segments that passes through more than one segment. 

 Do we not here have another condition, the type of musculature of 

 the legs, which shows a primitive condition? The sixth segment not 

 only gives rise to powerful flexor muscles going to the seventh but 

 sends strands to the flexor of the claws. The seventh gives rise 

 dorsally to the extensor of the claws and ventrally to a flexor of the 

 eighth segment and in addition sends powerful strands to the fiexor 

 of the claws. There is some indication of additional strands of muscle 

 fibers going to the flexor of the claws from the basal part of segment 

 eight. If the segment just proximal to the first knee bend be regarded 

 as the femur, or if the basal segment be regarded as the subcoxa, the 

 following names may be applied to the leg segments beginning at the 

 base: Subcoxa, coxa, coxal trochanter, femoral trochanter, femur, 

 patella, tibia, tarsus, foot (pretarsus). It should be added that the 

 tarsus has two or more pseudosegments and that the claws them- 



