ORGANS OF ATTACHMENT, 



synovial capsule, although most of the cranial bones have 

 lost even their connecting sutures, and most of the vertebrae 

 have their bodies united by free and secure synarthroses. 

 Less pressure being exerted on the joints in the light bodies 

 of birds than in the heavy bodies of mammalia, there is a 

 much thinner layer of elastic cartilage on the contiguous 

 ends of their bones than in quadrupeds, and from the light- 

 ness of their head, as in other oviparous vertebrata, com- 

 pared with that of most quadrupeds, they have no necessity 

 for a ligamentum nuchae to support it. The thick, firm, 

 elastic layer of fibro-cartilage interposed between the flat 

 bodies of the vertebrae of quadrupeds is the mode of arti- 

 culation which best corresponds with the strength and the 

 slow and limited motions required in that region of their 

 skeleton. The synovial capsules of the articular processes 

 of the vertebrae are more developed in the active trunks of 

 carnivorous and of climbing mammalia than in the more 

 weighty and motionless bodies of pachyderma and rumi- 

 nantia. The long anterior and posterior vertebral ligaments 

 are of great strength and elasticity along the pliant columns 

 of cetacea without and within the spinal canal, and in the 

 long and pliant tails of many quadrupeds we find the highly 

 moveable bodies of the coccygeal vertebrae united by syno- 

 vial capsules, to facilitate their motions. The heavy-headed 

 herbivorous quadrupeds have the ligamentum nuchee of 

 great size and strength, extending from the occipital 

 protuberance along the spinous processes of the dorsal, 

 and often of all the succeeding vertebrae to the coccygeal, 

 sending a pair of laminae downwards to be attached to each 

 spinous process. In the light-headed and muscular car- 

 nivorous species this ligament is very small, and generally 

 extends forwards only to the large spinous process of the 

 axis, and in many of the most active rodent and quadruma- 

 nous mammalia, no trace of this cervical ligament is per- 

 ceptible. In the strong extremities of heavy herbivorous 

 quadrupeds, where limited motions and secure articulations 

 are required, the capsular ligaments are less loose and 

 elastic than in the carnivora, where greater freedom and 

 extent of motion are necessary, and greater force of action. 

 Strong transverse ligaments pass in the elastic feet of rumi- 

 nating quadrupeds from the one penultimate phalanx to the 



