238 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



eration or defect. Monstrous ears, with defective helix or 

 lobules, are very common in idiots or imbeciles. The defect- 

 ive form, and absence of the lobule in the female Aztec cre- 

 tin, and in the case of dementia, are instances in point. The 

 ear of the male Aztec cretin is also defective, but it more 

 nearly resembles the ear of the chimpanzee. 20 A, March 

 16,1872,320. 



CHARACTERISTICS OF HIGHER GROUPS OF MAMMALS. 



In a memoir on the characteristics of the primary groups 

 of mammals, Professor Gill has given detailed descriptions 

 of all the orders and more comprehensive groups of the class 

 in question. He has accepted the division into three sub- 

 classes now generally recognized ; and the orders of the sub- 

 class of placental mammals, which embraces the bulk of the 

 class, are combined into two larger groups named super-or- 

 ders, which are distinguished by modifications of the brain, 

 and especially by differences in the development of the corpus 

 callosum, or great transverse commissure of the cerebrum. 

 The orders are distinguished by characteristics of the osseous 

 and nervous systems chiefly, and are as follows : 



SUB-CLASS MONODELPHIA. 



SUPER-ORDER EDUCABILIA. 



Four-footed Educabilia. 



1. Primates (man, monkeys, and lemurs). 



2. Ferce (carnivores, as cats, dogs, etc., and seals). 



3. Ungulates (ordinary hoofed animals, or cattle, camels, horses, etc.). 



4. Toxodonts (extinct). 



5. Hyracoids (the ' ' cony" of the Bible). 



6. Proboscideans (elephants and mastodons). 



Swimming Educabilia. 



7. Sirenians (manatus, dugong, etc.). 



8. Cetaceans (whales, porpoises, etc.). 



SUPER-ORDER INEDUOABII.IA. 



9. Chiropters (bats). 



10. Insectivores (shrews, moles, hedgehogs, etc.). 



11. Glires, or gnawers (mice, rabbits, etc.). 



12. Bruta, or edentates (ant-eaters, sloths, armadillos, etc.). 



SUB-CLASS DIDELPHIA. 



13. Marsupialia (opossums, kangaroos, etc.). 



SUB-CLASS ORNITHODELPniA. 



14. Monotremata (ornithorhynchus, or water-mole, and spiny ant-eater of 



Australia). 



The supposed relations of these orders are attempted to be 



