1901.] CHLAMTDOPHORUS TEUNCATtJS. 115 



not differ from previous descriptions, but it may be noted that the 

 component tendons of the tendo Achillis showed no signs of the 

 spiral twist around one another, that seems to occur to a greater 

 or less extent among the generality of mammals \ 



The Plantaris (text-figs. 16 & 17, ^^Z.), as in Dasypus', has no 

 direct attachment to the heel ; its tendon passes through a foramen 

 in the calcaneum (a gutter in Dasypus) and divides in the sole of 

 the foot into separate tendons inserted upon the proximal phalanges 

 and the expanded navicular. 



The Peroneus lonr/iis and hrevis (text-fig. IQ, p.l. &, p.hr.) differ 

 from the same muscles in the previously described specimens and in 

 Tatusia by respectively rising partly from the knee-cap and external 

 condyle of the femur as in Dasypus se-vcinctus ^. The peroneus 

 longus rises from the outer side of the knee-cap and from the 

 proximal pai-t of the outer surface of the fibula ; it is inserted as 

 usual upon the base of metatarsal i. 



The Peroneus brevis and extensor hrevis Y. rise by a common 

 origin from the external condyle of the femur, the external lateral 

 ligament, and the proximal part of the antero-lateral surface of the 

 fibula. The single belly terminates, in two delicate tendons, 

 inserted respectively on the base of the metatarsal and of the 

 penultimate phalanx of digit v. 



In view of the speculations that have arisen concerning the 

 origin of the external lateral ligament as a modification of a 

 femoral tendon of origin of the peroneus longus ^, one might 

 expect the origin of the peroneus brevis and extensor brevis T 

 from the ligament itself as well as from the femur to throve' some 

 light upon the question, but apparently it does not. For, with the 

 facts as they stand, it can be argued with equal propriety that the 

 hgament in question is a structure originally independent of the 

 muscle, but in this case serving as part of its area of attachment, or 

 that it is part of the femoral tendon of origin of the muscle in 

 process of transformation — functionally a ligament but not yet 

 completely divorced from the muscle. 



The Tibialis antiais (text-fig. 16, t.a.) had an origin (not men- 

 tioned by Macalister) from the anterior inner border of the fibula. 

 A similar origin is found in Dasypus, Cydothiirus, Bradypus, and 

 Choloepus % 



The Tibialis posticus accessorius (text-fig. 17, t.p. ii) took origin 

 from the proximal part of the hollow on the inner surface of the 

 fibula, and was inserted upon the inner surfaces of the astragalus. 

 According to Macalister's description, it rises from the tibia and is 

 inserted on the entocuneiform. 



The Extensor digitorwn communis (fig. 16, e.d.c.) sends a tendon 



^ Parsons : " On the Morphology of the Tendo Achillis." Journ. Anat. & 

 Physiol, xxviii. 1894, p. 414. 

 - Galton, 1. c. p. 556. 



3 Galton, 1. c. p. 559 ; also No. C 208, Physiol. Series, E. Coll. Surg. Museum, 

 ' Bland Sutton : ' Ligaments, their Nature and Morphology,' 1887, p. 34. 

 ' Macalister, 1. c. p. 268. Galton, I. c. p. 558. 



8* 



