646 



3958. The right patella. 



3959. The right tibia and fibula. 



They are anchylosed at their proximal ends. 



3960. The metacarpal bone of the outer digit of the right hind fin. 



Genus Phoca. 

 Dental formula : i ^, c -^, m ^=34. 



3961. The skeleton of the Harp-Seal (Phoca grwnlandicd). 



The vertebral formula is: 7 cervical, 15 dorsal, 5 lumbar, 4 sacral, and 8 caudal. Ten 

 pairs of ribs directly join the sternum, which consists of eight bones. The transverse pro- 

 cesses of the last cervical are imperforate. The neural arches of the middle dorsal vertebrae 

 are without spines and are very narrow, leaving wide unprotected intervals of the neural canal. 

 The bones of the neck are modified to allow of great extent and freedom of inflection. The 

 perforated transverse processes of the third to the sixth cervicals inclusive are remarkable for 

 the distinctness of their diapophysial and pleurapophysial parts. Metapophyses are developed 

 on the last five dorsal vertebrae : the strong hypapophysial ridge of the lumbar vertebrae 

 divides into two tuberous processes. These processes indicate the great development of the 

 anterior vertebral muscles, e. g. the ' longi colli ' and ' psoae,' and relate to the important share 

 which the vertebrae and muscles of the trunk take in the locomotion of the Seal-tribe, 

 especially when on dry land, where they may be called 'gastropods,' in respect of their 

 peculiar mode of progression. There is no trace of clavicle. The lower costa of the scapula 

 much exceeds the upper one in breadth. The spine terminates by a short and simple acro- 

 mion. The humerus is short and thick, and is remarkable for the great development of the 

 inner tuberosity and of the deltoid ridge, which is deeply excavated on its outer side. The 

 inner condyle is perforated. The scaphoid and lunar bones are connate. Although the pol- 

 lex or the first digit exceeds the third, fourth and fifth in length, it presents its characteristic 

 inferior number of phalanges, by which the inner border of the fin is rendered more resist- 

 ing. The pelvic arch is remarkable for the stunted development of the ilia, and the great 

 length of the ischia and pubes. The femur is equally peculiar for its shortness and breadth. 

 The tibia and fibula present the more usual proportions, and are anchylosed at their proxi- 

 mal ends. The bones of the foot are much developed, and are modified to form the basis of 

 a large and powerful fin : the middle toe is the shortest, and the rest increase in length to the 

 margins of the foot. In this skeleton the number of phalanges of the hallux equals that of 

 the other digits. 



Hunterian. 



