56 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. XIV. 



tendinous attachment to the posterior side of the inner tuberosity of the 

 fibula and the tendon continues broad through the muscle, which is 

 pinnatifid. An indistinct layer lies superficial to this part of the muscle 

 and is also pinnatifid, but in reverse direction, the tendon attaching to 

 the shaft of the tibia and the fibers radiating toward the fibula. This 

 may represent the so-called pronator tibiae, indications of which are 

 found also in Myrmecobius and Didelphis (Leche, p. 899), forms in 

 which there is some possibility of rotatory movements between tibia 

 and fibula, whereas in Ccenolestes such movements are quite precluded 

 by the closely appressed distal halves of the bones. The retention of 

 these muscles in C&nolestes, therefore, is possible evidence that the ar- 

 rangement of the bones is a recent specialization. This is partly nega- 

 tived, however, by the entire absence of the pronator quadratus in the 

 foreleg. There is no trace of a distal pronator tibiae such as is described 

 by Macalister (1870, p. 173) for Phascolomys, Sarcophilus, Phalangista, 

 and Perameles. 



MUSCLES OF THE HIND FOOT. 



The number and relations of the muscles of the hind foot, the so- 

 called intrinsic muscles, are broadly similar to those of various other 

 pentadactylous marsupials. The size and independence of the hallucal 

 adductor and the divided abductor indicis are noteworthy, as well as 

 the sesamoid origin of certain of the short flexors. Although the other 

 adductors and abductors are present it seems doubtful whether many of 

 them can be more than very slightly functional on account of the closely 

 appressed metatarsals. These are almost in contact proximally for 

 nearly half their length in such a way as to permit of only very slight 

 lateral motion. 



Lumbricales. These are fairly well developed, but of uneven size, 

 arising from the sides of the tendons of the flexor digitorum fibularis 

 and inserting with them at the ends of the toes. Each tendon has two of 

 these small muscles. Those on the tendons of the second, third and 

 fourth digits are progressively shorter and rise from the sides of the 

 tendons a considerable distance distad of their separation from the com- 

 mon tendon. Those of the tendon of the fifth digit are very unequal, the 

 outer being short and rising far distad while the inner is long and rises 

 as high as the point of separation of the tendon from the common 

 tendon. 



A single lumbrical rises on the medial side of the flexor digitorum 

 tibialis. Another thin muscle rises on the ventral surface of the common 

 tendon of the fibular flexor just above its digital divisions and sends 

 weak aponeurotic connection to the fourth digit and possibly also to 



