REPORT ON THE SEALS. 191 



In Arctocephalus they are inserted into the great trochanter to the outer side of the obturator 

 interims. 



The Obturator internus in Phoca vitulina arises from the internal surface of the obturator mem- 

 brane, and from the rim of bone around it, and forms a tendon which goes over the dorsal surface 

 of the ischial bar in its groove. The two gemelli meet over, surround, and conceal the tendon of 

 the obturator internus ; and all three are inserted together into the posterior border of the great 

 trochanter. 



In Arctocepilialus, after scraping away the gemelli and isolating the tendon, the muscle is found 

 to arise from the obturator membrane, &c, as in Phoca ; and is inserted to the inner side of the 

 insertion of the gemelli into the posterior upper end of the great trochanter of the femur. 



The Quadratics femoris is only found in Arctocephalus. It is triangular, and arises from the 

 dorsal half of the ischial bar, posterior to the gemellus inferior and anterior to the origin of the 

 semimembranosus. It passes forwards, outwards, and downwards, and is inserted by a tendon into 

 the lower half of the posterior border of the great trochanter. 



These three rotate the femur outwards, bringing the thigh near the pelvis. 



In Macrorhinus the dorsal part of the obturator externus represents the quadratus. In the 

 Phocinaj it is fused with the obturator externus and unrecognisable as the quadratus. 



The Muscles fkom the Pelvis to the Leg. — In the Phocinne, Macrorhinus leoninus, and 

 Arctocephalus gazella the gracilis, semimembranosus (in Phoca vitulina it has an anterior and 

 posterior part), semitendinosus (with two heads), and biceps (which has a long head, the biceps, 

 and a short head named the sacro-peroneus) are present. 



The Gracilis, also called symphysis tibialis in Lucae's plate, is a flat triangular muscle in the 

 Phocinre, stretching from the symphysis to the tibia. It arises from the symphysis pubis, and 

 radiates outwards to the lower leg, the superficial fibres only arising not from the bone but from 

 the linea alba. The posterior third of the latter is continuous with the fasciculi of the opposite side 

 over the symphysis. The anterior two-thirds is anterior to the pubic arch, the muscle of the right 

 side is beneath and overlapped by that of the left. It is inserted into the posterior two-thirds of 

 the ventral surface of the tibia, and many of the fibres end in a tendon near the shaft. The tendon of 

 insertion is combined with that of the semimembranosus and semitendinosus. In the substance of 

 the gracilis, near the ventral border of the tibia and parallel with it, is a long narrow tendon running 

 at right angles to its fibres. This is an indistinct white streak close to its anterior border, which 

 gradually widens and strengthens to a strong broadish tendon at its posterior border; at the bend 

 of the anterior surface of the astragalus it expands, forming, with the prolongations backwards of 

 the combined tendons of insertion of the semimembranosus and seniitendinosus, and gracilis, the 

 plantar fascia. 



In Macrorhinus leoninus it arises from the symphysis pubis by the fibres of its deep surface, 

 from the linea alba in front of the pubis by the intermediate fibres, and by the superficial fibres 

 from the ligament stretching between the pubic bones. The fibres opposite the pubes are blended 

 with those of the opposite side. It is inserted into the posterior half of the tibia. 



In Arctocephalus gazella it arises from the symphysis pubis, and from the ligament between the 

 pubic bones. The superficial fibres are continuous with those of the opposite side, and none of the 

 fibres reach further forward than the symphysis. It is inserted into the middle third of the ventral 



