52 THE BONES. 



life ; but commence to form about the fourth month of conception, by a process 

 of resorption, which removes the spongy substance interposed between the two 

 compact tables of bone, and may even cause the destruction of the internal table. 

 The sinuses enlarge with age, and remain during life separated from one another 

 by a vertical septum. 



Differential Characters in the Frontal Bone of other Animals. 



A. Ox, Sheep, Goat. — In Eumiaants, the frontal bone does not come in contact with 

 the temporal or palatine bones (Figs. 30, 31, 32). 



In the Ox, this bone is extremely developed, occupying alone nearly one-half of the anterior 

 surface of the head. It is particularly distinguished by: 1. Its great thickness. 2, The 



Fig. 30. 



ox's head (anterior face). 



1, Mastoid process ; 2, superciliary, or supra-orbital foramen ; 3, malar bone ; 4, lachrymal 



bone ; 5, maxillary spine ; 6, inferior orifice of the supermaxillo-dental canal. 



osseous conical cores which support the horns. These eminences, more or less long and curved, 

 very rugged, perforated by foramina, and grooved by small vascular channels, are detached 

 outwards from each side of the bone, near the summit of the head. The proce.-^ses which form 

 the orbital arches rest by their summits on the zygomatic bone. The supra-orbital foramen is 

 transforraeil into a veritable and frequently multiple canal ; its anterior orifice opens into a 

 vasculo-nervous groove, which ascends towards the base of the horns, and descends to near the 

 lower border of the bone. Between this groove and the base of the orbital arch is the frontal 

 boss. Thp orbital foramen entirely belongs to this bone. The inferior border is deeply notched 

 in its middle to receive the nasal bones; the frontal sinuses are prolonged into the horn-cores, 

 the parietal bone, and even into the occipital bone. , 



The frontal bones of the Angus breed of cattle (^polled cattle) have no horn-cores. The 

 ablation in the calf of the periosteum, followed by cauterization, at the point where appear 

 the osseous prolongations which serve as bases for the horns, prevents the development of 

 these appendages. Cornevin mentions that a farmer of Haute Marne has in this way muti- 

 lated the cattle bred on his farm for twenty-three years, and yet the mutilation has not become 

 hereditary. Fig. 31, representing the head of an Ox so mutilated, shows that the removal of the 



