1885.] MYOLOGY OF THE WATER-OPOSSUM. 15 



Psoas parvus. — Very large, arising from sides of bodies of last 

 three dorsal and first two lumbar vertebrae by tendinous fibres, and 

 fronts of next four vertebrae by fleshy fibres. It is inserted by a 

 narrow tendon into ilio-pectineal line just outside marsupial bone. 



Iliacus. — Arises from iliac fossa. Inserted by muscular and 

 tendinous fibres into lesser trochanter of femur and into surface of 

 bone beneath it, its lower fibres being closely connected with tendon 

 of psoas. 



Gracilis. — Arises from lower two thirds of pubic symphysis and 

 from a small portion of its descending ramus. It is inserted into 

 inner surface of tibia by strong fibres at its upper part, and by a 

 fascia closely united to lower part of insertion of semitendinosus 

 below this. 



Pectineus consists of two small flat slips united at their origin : — 

 1. Arises from outer angle of base of marsupial bone by a narrow 

 tendon. 2. Arises from pubes between former slip and insertion 

 of psoas parvus. They are inserted into ujiper half of linea aspera 

 superficial to adductor brevis, a narrow space existing between 

 their insertions. 



Adductor brevis. — Arises from a small portion of pubic symphysis, 

 ascending ramus of pubes, and inner pan of marsupial bone. It is 

 inserted into middle lip of linea aspera for its upper half. 



Adductor magnus. — Extensive origin from lower part of pubic 

 sj'mphysis, rami of pubes and ischium, and ischial tuberosity under 

 cover of gracilis, semimembranosus, and semitendinosus. Its fibres 

 converge and are inserted into triangular surface at lower third of 

 linea aspera. The muscle has the appearance of being enfolded 

 on itself, the fibres from the symphysis pubis and upper part of 

 ramus forming a thin strap-like band which crosses the other fibres 

 obliquely. 



Adductor lorigus. — Arises from pubic symphysis between origins of 

 adductors brevis and magnus. It is inserted into lower half of linea 

 aspera and inner condyle. 



Quadratus femoris. — Arises from ischial tuberosity. Inserted 

 tween greater and lesser trochanters of femur. 



Gastrocnemius internus. — Arises from posterior part of inner con- 

 dyle of femur. Its tendon is grooved on its deeji aspect and 

 embraces tendon of gastrocnemius externus. It is inserted on 

 outer side of posterior surface of os calcis. 



Gastrocnemius externus. — Much larger than preceding muscle. 

 It arises from external condyle of femur, receiving a band of fibres 

 which arises from the sesamoid bone, which articulates with the 

 head of the fibula. It forms a thick belly, which is partially 

 separable into two parts, and is inserted into os calcis on inner side 

 of gastrocnemius internus. 



Plantaris. — Arises in close connection with gastrocnemius externus 

 from sesamoid bone, passes under gastrocnemei, and is inserted 

 into fascia on inner side of foot. 



Pop/iteus. — Arises by narrow tendon from external condyle of 

 femur. Inserted i.ito posterior surface of tibia at its upper half. 



