54 PROFESSOR STRUTHERS. 



attached to the outer edge of the femur, the inner part to form 

 a fibrous sheet covering and adhering to the superficial surface 

 of the femur. These latter parts, all however forming a con- 

 tinuous sheet, thus strap down the femur, and enable the 

 caudal mass to act in part as a retractor of the femur, tighten- 

 ing it backwards and also outwards. This backward connection 

 of the femur is strengthened by a deeper fibrous stratum, pass- 

 ing back from the femur to the pelvic bone and to the outer 

 part of the great interpelvic ligament. Near the femur these 

 posterior fibrous connections are J to J inch thick, farther 

 back the deeper stratum is about -J inch thick. The latter 

 will serve purely as a ligament. 



Anterior Connections of the Pelvic Bone. The arrangement 

 of the anterior or trunk muscular mass in Megaptera differs 

 from that in B. musculus and still more from that in Mysticetus. 

 In the latter, in a 33-feet-long Mysticetus, a great mass of flesh, 

 10 inches by 3 inches, came back to be attached, fleshy, to 

 the beak, to the long nearly parallel femur, and to the tibia, 

 separating into internal and external parts. In the B. mus- 

 culus also there was a very large fleshy mass here, about 9 

 inches by 6, but most of it attached only to a great fibrous 

 septum, to which also is attached a portion of the posterior 

 caudal mass. To the anterior half of the beak was directly 

 attached a mass of flesh 4 inches by 1 inch, and separately at 

 the outer part, just in front of the promontory, a tendon, 1J 

 inch broad, which after a course of 1J inch gave off a large 

 lateral anterior muscle. In Megaptera this latter, 1J inch in 

 breadth here, strengthened by a part arising on the outer side 

 of the promontory, is the only structure I saw attached to the 

 beak of the pelvic bone (fig. 15, i.i.). It was fibrous for 4 inches 

 forwards, and was joined on its outer side by the part of the 

 tendinous prolongation of the posterior caudal mass above 

 noticed as skirting the pelvic bone externally. In connection 

 with this difference in the soft parts attached to the beak in 

 these two species of finners, is to be remarked the shortness 

 of the beak, compared with the body of the pelvic bone, in 

 Megaptera. Measured from the middle of the outer edge of 

 the promontory, the lengths of the beak and the body are, 

 respectively, in the 50-feet-long B. musculus 9 inches and 5 



