55G CETACEA. 



large number of lumbar and caudal vertebrae, the latter having 

 chevron bones ; by the absence of sacral vertebrae and by the 

 thick fibrous intervertebral discs and the absence of articulating 

 processes on the posterior dorsal and hinder vertebrae. The 

 epiphyses of the vertebrae and of other bones remain distinct 

 for some time. The number of vertebrae is C7, D9-1C), L3-24, 

 C18-30. The sternum tends to be short and but few ribs join 

 it. The ribs are distinguished by their loose articulation both 

 with sternum and vertebral column. There are no clavicles. 

 The scapula is remarkable for the position of the spine close to 

 the anterior border. The humerus is short and freely moveable 

 upon the scapula, but the other joints of the fore-limb are im- 

 perfect. The radius and ulna are flattened and short. The 

 carpal bones are more or less normal and embedded in fibrous 

 tissue, but they vary considerably. In the whalebone whales 

 many of the elements of the manus (including the phalanges) 

 remain cartilaginous. There are generally five digits, but 

 in most of the whalelione whales there are only four.* There 

 are more tlian three phalanges in some of the digits : this always 

 happens in digits Nos. 2 and 3, in which the number may mount 

 to fourteen or more. The phalanges have epiphyses at both 

 ends. 



The pelvis is represented by a pair of bones placed longitu- 

 dinally at some distance from the vertebral column, and pro- 

 bably representing the ischia. The crura penis are attached to 

 them, and in the whalebone whales there may also be a trace 

 of the femur in the form of a short bony rod attached to their 

 outer sides, to which may be added the trace of a tibia. 



The brain is very large and its surface richly convoluted. 

 It is the largest and most convoluted brain found beneath the 

 Primates. The lateral ventricle shows a trace of a posterior 

 cornu. The olfactory lobes and nerves are absent or small. 



Tlie soft palate is long and inuscular. The glottis is funnel- 

 shaped, owing to the prolongation of the epiglottis and arytenoid 

 cartilages, which project into the narial passage. When this 

 spout-like structure is embraced by the soft palate there is a 



* In such cases it lias been said that it is digit No. 3 which has dropped 

 out; vide Kiikenthal {Denkschr. Med. Nat. Ges. Jena, ?•, 1889, p. 1, and 

 3, 1893, p. 221) who maintains that in a foetal Bnlaenoptera there is a trace 

 of a digit, ■which does not reach the carpus, between digits No'^. 2 and 3, 

 and that in the pentadactyle Balaena the first digit is a prepollex. 



