EVOLUTION AS SEEN IN SEROLOGICAL TESTS 119 



Order Rodentia (albino rat, guinea pig) and of the representative of Or- 

 der Primates (man) being of less magnitude. 



The accompanying bar graph (Fig. 6.4) summarizes the results of the 

 test shown in Fig. 6.3 and of another test performed with antiserum ob- 

 tained at another time from the same four cocks. It is evident that the re- 

 sults to date confirm the wisdom of separating lagomorphs from rodents 



FIG. 6.4. Relative serological relationships of several 

 mammals to the domestic rabbit. Turbidity (photronreflectom- 

 eter) tests. (From Moody, Cochran, and Drugg, "Serologi- 

 cal evidence on lagomorph relationships," Evolution, Vol. 3, 

 1949, p. 30.) 



and suggest that lagomorphs are not more closely related to rodents than 

 they are to other orders of mammals. It is tempting to see in these results 

 evidence of greater affinity between lagomorphs and artiodactyls than 

 exists between lagomorphs and any other order studied. Such a con- 

 clusion, while suggested, would be premature, however; more tests and 

 tests including representatives of a greater number of orders of mammals 

 are needed before we can state with certainty that lagomorphs are more 

 closely allied to one order than they are to any other one. 



Porcupines 



Porcupines live in North and South America and in Africa. Though 

 they both have quills, New World and Old World porcupines diflfer in 

 many respects. For example, African porcupines have much the larger 

 quills. African porcupines burrow in the ground; American porcupines live 

 in trees. Nevertheless, skeletal similarities result in their traditionally being 

 classed together as "hystricomorph" rodents, a term which also includes a 

 variety of other South American rodents, such as guinea pigs, agoutis, 

 pacas, and capybaras (Fig. 12.1, p. 260). Evidence indicates that porcu- 



