THE PHYLUM CHORDATA 



.^r^-^^^^ 



^^'^4 



FERUNGULATA 



Figure 62. Representative Mammalian Types. A, shrew, similar to the primitive 

 placental progenitor; B, bat, the only mammal capable of true flight; C, armadillo; D, 

 mole; E, squirrel; F, rabbit; G, horse; H, deer; 7, racoon; /, porpoise; K, opossum. A-D, 

 cohort Unguiculata; £ and F, cohort Glires; G-l, cohort Ferungulata; /, cohort Mutica. 

 The opossum, being a marsupial, is of remote and uncertain relationship to any of the 

 others. 



the degree of assurance with which such an ancestry can be postulated. 

 ( Because arrays of orders within the class are quite distinct from one an- 

 other, Simpson, whose classification of the mammals is generally accepted, 

 advocates the use of the cohort as a category intermediate between order 

 and class.) 



175 



