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SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 97 



and it is only in their later development that they assume the structure 

 characteristic of the adult appendages in each group. 



An onychophoran leg (fig. 31 A) is a hollow, conical outgrowth 

 of the body wall terminating in a small pedal lobe bearing a pair of 

 decurved claws. The leg integument is thrown into permanent circular 

 folds, which on the thick basal part of the limb are covered with 



19a 16 



17a c 19b ci 



J^ *^ 19b id e i- v_T i/a c lyb d e 



Fig. 31. — Structure and musculature of an onychophoran leg, Peripatoides 

 novae -zealatidiae Hutton. 



A, anterior view of a leg. B, lateral view of distal part of leg. C, horizontal 

 section of basal part of leg. D, section of more distal part of leg. E, diagram- 

 matic vertical section of distal part of leg. F, mesal view of leg. G, section 

 of entire leg in transverse plane of body. 



a, b, c, d, distal nontuberculate rings of leg; e, claw-bearing pedal lobe; Npr, 

 nephropore ; Un, claws ; 14, transverse muscle of leg base ; 15, peripheral muscles 

 of basal part of leg ; 16, anteroposterior septal muscles of leg ; 17, flexor muscle 

 of leg ; 17a, flexor of distal leg rings ; 18, circular muscles of foot ; 19a, 19b, 

 two-branched retractor of claws. 



bristle-bearing tubercles. The distal folds, however, form distinct 

 segmentlike rings (A, B, a, b, c, d) and are devoid of tubercles. 

 The pedal lobe (<?) appears to be a larger terminal ring bearing the 

 claws (Un). 



The leg is movable anteriorly and posteriorly on the obliquely 

 transverse axis of its base by the four somatic muscles (fig. 30, 7, 

 8, II, 12) that converge from the body wall into its basal opening. 

 These muscles undoubtedly serve principally as promotors and re- 



