144 PHYSIOLOGICAL SERIES. 



C. 197. Right foot of a Rook (Trypanocorax fruyilegus}. The 

 tendon of the flexor longus crosses superficial to that of the 

 profundus in the same manner as in the previous specimen, 

 but is not united to it by a vinculum. It goes to I. The 

 profundus tendon divides at the base of the toes into three 

 tendons for n., m., and IV. digits respectively. This 

 arrangement is found in most Passerine birds. 0. 0. 

 G4 Y i. Presented l>y P. Sharpe, Esq. 



C. 198. Muscles of the left hind-limb of a Duck-billed Platypus 

 (Ornithorhynchus anatinus). The gluteus maxiuius (of 

 \vhich the origin and insertion only have been preserved) 

 is of great size, and is remarkable for its insertion to the 

 posterior surface of both bones of the shank close above the 

 ankle. The gluteus minimus is much fasciculated and is 

 supplied by both iliac and crural nerves, in this feature 

 (characteristic of the ilio-femoralis of Reptiles and Urodeles) 

 the Monotremes differ from all other Mammals. The 

 gastrocnemius is single represented only by the inner head; 

 it is joined in the middle of the shank by the soleus (thought 

 by some to be the outer gastrocnemial head with a fibular 

 origin), and the two together form the tendo AchiJlis. The 

 flexor fibularis in the absence of the flexor tibialis sends 

 tendons to each digit. The flexor brevis rises partly from 

 the common tendon of the fibularis, partly from the cal- 

 caneutn. The first part supplies n., the calcaneal head IV. 

 & v. The extensor longus digitorum is double. A green 

 rod has been placed beneath the tendons of the extensor 

 longus. A blue rod beneath those of the extensor brevis. 

 Ooues, Communic. Essex Instit., vol. vi. 1871, p. 159. 



C. 199. Distal part of the left hind-limb of a Duck-billed 

 Platypus ( Ornithorhynchus anatinus}, showing the deeper 

 muscles. The short extensors rise entirely from the fibula. 

 They are two in number i. Extensor brevis V. dig., which 

 probably also potentially includes the peroneus brevis 

 its tendon bifurcates upon the dorsum of metatarsal V. ; one 

 branch, representing the peroneus brevis, is inserted upon 

 the apex of metatarsal v., the other upon the phalanges, 

 ii. Extensor brevis digitorum, rising beneath the preceding 



