1 8 Annals Entomological Society of America [Vol.11, 



the whole femur nearer towards the trochanter. 2. 71/. flexor 

 femoris bilobatus (Fig. 3. fl. f. b.) consists of two symmetrical 

 halves arising from the hyposynaxial surface of the trochanter. 

 Its numerous short tendons are inserted close together into the 

 same edge with the flexor longus. 



Femur. Enclosed in the femur we find two muscles closely 

 resembling those of the trochanter, i. M. flexor patellae longus 

 (Fig. 3. fl. p. 1.) has two proximal tendons one of which arises 

 from the distal end of the hyposynaxial surface of the trochanter 

 and the other from the corresponding proximal end of the femur. 

 The fibres soon form one spindle-like muscle which is inserted 

 with a long tendon into the proximal hypo-edge of the patella. 



2. M. flexor patellae hilohatus (Fig. 3. fl. p. b.) is in every respect 

 homologous with the corresponding muscle of the trochanter, but 

 as the flexor femoris raises the femur, while the flexor patellae 

 lowers the patella together with the tibia, the two homologous 

 muscles arise from the opposite surfaces. It is the articulation 

 of the segments that determines the position of muscles. The 

 musculus flexor patellae bilobatus consisting of two symmetrical 

 halves arises therefore from the entire episynaxial surface of the 

 femur and its numerous short tendons are inserted close together 

 into the proximal hypo-edge of the patella on both sides of the 

 long flexor. 



Patella. The articulation of the patella with the tibia is 

 such as to allow of scarcely any motion. Notwithstanding this 

 we find three muscles in the patella. Two of these are symmetri- 

 cal and consist of parallel fibres arising from the episynaxial and 

 the pro- and retrosymmetrical surfaces of the segment. Each 

 separate fibre is inserted apparently without a tendon into the 

 proximal pro- and retro-edges of the tibia. These two muscles 

 are: i, M . promotor tibiae, and 2, M . retractor tibiae (Fig. 3. r. t.) 

 The third muscle which is also to all appearances functionless is 



3, M. flexor tibiae. It arises from the proximal end of the episyn- 

 axial surface of the patella and is conical in shape. Its long cylin- 

 drical tendon is inserted into the middle of the proximal hypo- 

 edge of the tibia. This muscle is entirely overlooked by previous 

 investigators although it may easih^ be found in spiders of differ- 

 ent families and all sizes. 



TiBL\. The muscles of the tibia are in every respect homolo- 

 gous with those of the femur. A number of fibres arise from the 

 proximal surface of the patella without however forming a tendon, 



