4 PROFESSOR OWEN ON THE OSTEOLOGY OF 



The greater relative breadth and length of the coracoid process in the Gorilla is in 

 adaptation to the prodigious muscular powers of the arm ; but in all the more essential 

 points in which the scapula differs from that of the Chimpanzee, it more nearly resembles 

 the scapula of the Human subject. 



Clavicle. — Plate II. 



The clavicle of the Gorilla (fig. 1) presents a slight sigmoid curve, but in a less 

 degree than in Man {ib. figs. 2 & 4), the body and sternal portion being straighter : it 

 is thicker in proportion to its length. In the horizontal plane the curve of the sternal 

 end is concave backward, that of the acromial end forward ; and this end is slightly 

 bent downward to join the acromion. The expansion for the sternal articulation is 

 considerable ; and in the old male there is a process behind, close to this surface, in- 

 creasing the attachment of the cleido-mastoideus muscle and the rhomboid ligament. 

 Below and close to this process is the depression for the cartilage of the first rib. The 

 body of the bone is trihedral, smooth on the upper and outer facets, rather rough below. 

 Near the sternal expansion is the rough surface for the attachment of the rhomboid 

 ligament. The acromial expansion is obscurely divided into two rough tracts above, 

 for the trapezius and deltoid muscles : it is flattened beneath, with a rough tract for the 

 trapezoid lij^ament. 



In the Chimpanzee (fig 3) the trihedral shaft is usually straighter than in the specimen 

 figured, and the clavicle is always thicker in proportion to its length than in Man. The 

 under surface of the acromial expansion is slightly concave. In the Gorilla that surface 

 is more like that in Man. 



The Human clavicle (fig. 2, European, and 4, Austrahan) is more slender in proportion 

 to its length, and its curves, like those of the italic/, are always better marked than in 

 the great Apes : the tubercle for the conoid ligament is usually more developed. 



Humerus. — Plate III. 



The humerus of the Gorilla (figs. 1-4), though surpassing so much in length that 

 of Man {ib. fig. 8), is nevertheless thicker in proportion, and, in the old male, much 

 stronger in all its ridges and processes ; especially at the lower extremity, the trans- 

 verse diameter of which surpasses that of the upper extremity of the bone in a greater 

 degree than in Man. The articular head (fig. 2, b) closely resembles that of Man's 

 humerus in shape and direction; the peripheral constriction or 'anatomical neck' is 

 better marked : both tuberosities are relatively greater than in Man — the ' lesser ' one (d) 

 more especially, the lower end of which encroaches, in a front view of the bone, upon 

 the contour curve (fig. 1 , a) by which the lower part of the neck passes at the usual obtuse 

 angle from the shaft to the head : the surfaces on the greater tuberosity for the insertion of 

 the supraspinatus and infraspinatus (e) are well defined. The bicipital groove is deep, and 

 the margin of the lesser tuberosity arches over it in the old male : the groove passes down- 



