REPORT OP ASSISTANT SECRETARY. 171 



labeled, tlius iciuloring' it possible to recogiii/.e the coiTespondiiigr bones 

 of eai'li almost at a glance. 



(h) ISpecial homologies; the shnll. — Sknlls of sturgeon, gar i)ike, 

 grouper, nienoponia, frog, boa constrictor, turtle, alligator, penguin, 

 goat, and puma, liaviug tbe correspouding bones similarly colored. 

 While this plau is not uew, special attention was given to securing a 

 harmonious color scheme, and the smaller skulls were represented by 

 accurately enlarged models, thus showing details that would otherwise 

 have been invisible. 



{(■) Special homoJo</ic.s; ihr Intih.-i. — Articulated limbs of grouper, sea 

 turtle, alligator, eagle, and dog, having the larger bones labeled and 

 the smaller bones numbered, the specimens being accompanied by cor- 

 respondingly numbered labels giving* the names of the various bones 

 of the wrist and aidile. Limbs of fish, sea turtle, manatee, cormorant, 

 great auk, sloth, bat, monkey, and man, showing the homologies of 

 limbs specially modified for various nu'thods of locomotion, JNIauus 

 and i)es of a horse, camel, moose, tapir, seal, bear, and lion, with the 

 larger bones labeled and the smaller numbered alike, intended to make 

 clear the corresi)ondence of ])arts in mammals having from 1 to .") digits. 



(2) U^CATION, GItOWTll, AXn STRUCTl'HK OK TKKTII. 



Series of skulls of mammals, reptiles, and fishes, exhibiting the teeth 

 in various stages of growth, many having the outer surface so cut away 

 as to show the y<^'ung teeth not yet in place. Specimens illustrating the 

 mode in which the teeth are replaced in some animals, and single teeth, 

 or sections of teeth, displaying the varying proportions and disposition 

 of the dentine, enamel, and cement, as well as some of the simpler and 

 some of the more complicated patterns of tooth structure. 



(3) STRrCTlHE AXI> OROWTH OF HORNS. 



Examples of horns which are merely outgrowths of the epidermis, 

 as is the case in the rhinoceros; those which are permanent outgrowths 

 of the frontal bones covered with hard epidermal structures, such as 

 are found in sheep, goats, and oxen; and those which, as in the deer, 

 are outgrowths of the frontal bones and are grown and shed annually. 

 Sections of these various classes of horns are shown also. 



ll> STIUCTURE OK TIIK !.ONC; BONKS. 



A series of bisected humeri and femora exhibiting the light, hollow, 

 structure of the long bones in animals of rapid movement, and the more 

 or less dense character of the limb bones of aquatic animals or those of 

 sluggish movements. 



(5) STRCCTURAL VARIATIONS OK DOMESTIC ANIMALS. 



Series of skulls of dogs, showing something of the cranial variations 

 in different breeds. Series of skeletons illustrating the more marked 



