OF THE WOMBAT, KOALA, AND PHALANGERS. 881 



Minimus does not differ in any essential in the animals described 

 in this paper except for the degree of adhesion to the medins. 

 The Gluteus Quartus is present in all. 



Pyriformis : — In all forms this is a strong triangular muscle 

 arising from the side of the sacrum and running to the summit 

 of the great trochanter of the femur. The Obturator Externus is 

 likewise similar in all, and is large. 



Ohturator Internus: — This muscle is absent in Phascolomys, but 

 present in all other forms. The Gemelli are present in all. They 

 are both enormous in Phalanger, of moderate size in Phascolarctos, 

 and the inferior one is large in Phascolomys. 



The Qiuidratus Femoris is absent in Phascolomys. In Phasco- 

 larctos it arises entirely from the great sciatic ligament. In 

 Phalanger it arises from the tuber ischii. The insertion is into 

 the posterior border of the great trochanter. 



Sartorius : — In the Marsupialia this muscle acts as an extensor, 

 and an interval, filled with fascia, is present between its vipper 

 part and the quadriceps. It arises in all from the anterior 

 superior iliac spine ; and it is inserted into the inner side of the 

 quadriceps tendon {Phascolarctos), or the inner aspect of the patella 

 and knee-joint {Phalanger, Pseiodochirus, Phascolomys). 



Quadriceps Extensor : — The rectus femoris has only the straight 

 head in Phascolomys, but both heads are present in Phascolarctos, 

 Pseudochirus, and Phalanger. In the other elements these 

 animals are all essentially similar, and the vastus externus 

 component is large. The tendon is inserted in all into the tibia.. 

 It contains a cartilaginous patella in Phascolomys, Phalanger, and 

 Pseudochirus, but none in Phascolarctos. Waterhouse (17) stated 

 that Phascolomys also has no patella, and used this character 

 among others to show that they are related. As many observers 

 have recorded the presence of the patella in the Wombat, it is 

 evident that this is not a character linking it to the Koala, as 

 Waterhouse believed. 



Gracilis : — When the skin is removed it is seen that the muscles 

 on the mesial aspect of the thigh are concealed by the gracilis to 

 a variable extent. It arises from the symphysis pubis and a 

 variable extent of the descending ramus, and from the mesial 

 extremity of the marsupia.l bone. It is inserted into the 

 proximal half of the mesial border of the shaft of the tibia. In 

 Phascolomys, Phalanger, and Pseudochirus it goes to the proximal 

 half of the tibi^, but in Phascolarctos it only runs to the proximal 

 third. 



Biceps Crta'is : — In Phascolarctos the biceps and semimem- 

 branosus have a strong, common tendon of origin from the ischial 

 tuberosity and caudal vertebrae. The biceps is thin and triangular, 

 and inserted into the fascia over the proximal two-thirds of the 

 fibula. No femoral component enters into the biceps. Young 

 (14) points out that the nature and extent of the insertion are 

 associated with the semi-flexed attitude of the limb. In Phalanger 

 the muscle arises from the ischial tuberosity, along with semi- 



