396 Harris Hawthorne Wilder, 



where the epiphysis joins the sliaft, including in its field of attach- 

 ment both cartilage and bone. 



C. Muscles of the distal portion. 



1. Dorsal aspect of forearm and hand. 



M. hum eromet acarpalis (hm). This is the large super- 

 ficial muscle, triangulär in shape, that Covers the central part of 

 the dorsal surface, between Mm. extensor radialis superficialis and 

 extensor ulnaris. It arises from the lateral condyle of the numerus 

 and diverges fan-like to about the level of the distal row of carpal 

 bones, where it becomes divided into three main slips, corresponding 

 to the intervals between the digits. Closely associated with the 

 outer one of the three main slips there is situated an accessory slip, 

 which continues the series upon the ulnar side. It arises by a 

 tendon of its own that lies upon the ulnar side of the main muscle 

 in the form of a fine thread, and gives rise, not only to the fibers 

 that form the accessory slip, but also to a few of the most ulnar 

 fibers of the main bündle adjacent to it. The tendon lies closely 

 approximated to that of the ulnar extensor, and in some cases it 

 seems as though there was a direct connection between the two 

 muscles. 



Arrived at the interdigital Spaces each of the three main slips 

 divides distally into two, which insert by small tendons into the lateral 

 angles at the bases of two adjacent metacarpals. Thus the two 

 tendons of the most radial slip supply the ulnar side of digit II and 

 the radial side of digit III; those of the second the ulnar side of 

 III and the radial side of IV ; and those of the third the ulnar side 

 of IV and the radial side of V. The accessory slip passes to the 

 outer (ulnar) side of the origin of M. extensor brevis V and inserts 

 into the outer (ulnar) side of the base of metacarpale V. J ), It thus 



1) In the foot this accessory slip seems to have been noticed by 

 several observers, but its presence in the hand also has been overlooked, 

 although, in Necturus at least, the two members are exactly alike in this 

 respect. Thus Humpbrey, describing the foot of Cryptobranchus, calls 

 it "M. peroneus tertius", and Hoffmann describes it as a general Uro- 

 delan muscle under the name of "M. femoro-tarsali-fibulare", but con- 

 siders it a part of the "Femoro-digiti I — V" (= my femorometatarsalis). 

 OSAWA mentions the statements of both HüMPHREY and Hoffmann, but 



