MAY, 1921. AMERICAN MARSUPIAL, C^NOLESTES OSGOOD. 61 



Peramys and Macropus. That this is not an ideal method of com- 

 parative work can be apparent to no one more fully than the author; 

 but, it is the best that circumstances permit and if small errors have 

 crept in it is hoped that they will not seriously affect general con- 

 clusions. The nomenclature adopted has been that of Bronn's Thier- 

 reich with occasional changes where it seemed feasible to conform to the 

 BNA terms. 



Features in the myology of C&nolestes which seem especially note- 

 worthy are as follows: 



Trapezius divided into spinotrapezius and acromiotrapezius. 



Rhomboideus divided. 



Dorso-cuticularis present. 



Distinct rectus capitis posterior superficialis, 



Pterygoideus externus relatively large and bicipital. 



Subclavius not extending to scapular spine. 



Median head of triceps brachii distinct. 



Origin of supinator brews including a sesamoid. 



Pronator quadratus absent. 



Distinct caudo-femoralis present. 



Femoro-coccygeus practically distinct from glutens maximus. 



Glutens medius partially divided into two layers. 



Sartorius on inner side of thigh, much reduced, and originating from 

 Poupart's ligament. 



Extensor carpi ulnaris with ulnar as well as humeral origin. 



Radial extensors of carpus separate from each other. 



Median and lateral heads of gastrocnemius partly united. 



Fibular divisions of extensor brew's digitorum distinct from each other. 



Pedal extensor hallucis brews well-developed. 



Flexor accessories present. 



Pronator tibiae partly separate from popliteus. 



Short flexors of second and third toes arising from a sesamoid. 



URINOGENITAL SYSTEM. 



The interesting urinogenital system has been studied only by gross 

 dissection and the use of the binocular microscope. With the scanty 

 material available and the means at hand, no other course seemed pos- 

 sible. It is to be regretted that serial sections could not be obtained of 

 the embryo. One of the imperfect females examined was pregnant, 

 having three embryos, two in the right uterus, and one in the left. The 

 uteri were greatly expanded and the foetuses lay surrounded by their 



