OSTEOLOGY OF ANTARCTIC SEALS. 27 



non-articular neck for attachment of the ligamentum teres. Dr KEITH, in Human 

 Embryology and Morphology, p. 385, states: "The ligamentum teres is isolated 

 from the capsule by the development of the head of the femur, which expands as a wing 

 on each side of the ligamentum teres, and by fusion of the wings Isolates it from the 

 capsule." In the Ross seal femur the wings have not yet met; hence, according to 

 KEITH'S view, the ligamentum teres would still be in connection with the capsule. (See 



%- 6.) 



The trochanter major was a broad, rough prominence projecting from the outer side of 

 the junction of the neck of the bone with the shaft. There was no trace of a trochanter 

 minor, as is to be found in Otaria Jubata ; neither was there a third trochanter. 



The shaft, flat and expanded, possessed an anterior and a posterior surface, both 

 being very slightly rounded and devoid of muscular ridges. The outer border was 

 short and concave, the inner convex and very rough for muscular attachment. 



At the posterior end of the bone, the trochlear surface for the patella was flattened 

 and ascended as high on its outer as on the inner side. It was quite distinct from the 

 condylar surface, but closely approximated to the external one, being separated by a 

 very narrow groove. 



The internal condylar surface was flat and circular, the outer one oval and slightly 

 convex. 



The intercondyloid fossa was shallow. 



The patella was 34 mm. long and 24'5 mm. broad. It was oval in form, and its 

 articular surface was slightly concave, and did not exhibit any subdivision into special 

 articular areas. Its anterior end was much thicker than the posterior. 



The tibia and fibula were fused together at their upper ends. The tibia measured 

 247*5 mm. Its upper end was elongated transversely and possessed two articular areas 

 for the condyles of the femur, separated by a rough intermediate area. The shaft was 

 slightly curved, flat and smooth on its ventral aspect, deeply concave on its dorsal 

 aspect for origin of the tibialis posticus muscle. The nutrient foramen was a large one. 

 The inner border was broad and rough, the outer one thin and rounded. The lower end 

 was not united with the shaft, and from it projected a slight malleolus, which was non- 

 articular. The ventral and dorsal aspects of the lower end were deeply grooved, while 

 the articular area for astragalus was reniform and concave. 



The fibula was 233 mm. in length. The upper end was fused with the tibia, whilst 

 the lower end was grooved on the outer side by the peroneal tendons, and had on its 

 inner aspect an oval facet for outer surface of astragalus. The shaft was straight, 

 and its surface broad for muscular origins. The lower epiphysis was not united to 



the shaft 



Tibia- Femoral Index. 



Length of tibia x 100 

 Length of femur 



Ross Seal. Weddell Seal. Leopard Seal. 



217-1 203-9 213-5 



(BOY. SOC. EDIN. TRANS., VOL. XLVIL, 197.) 



