92 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 7.f 



In no respect, perhaps, does the tendency for subdivision of the 

 muscles of the posterior limb of Zalophus and fusion of those of 

 Phoca appear more pronounced than in the adductor muscles and 

 certain others near them. The adductors, however, when these show 

 complexity, is one of the groups which it is as yet not only unwise 

 but actually misleading to attempt to homologize too precisely with 

 the human divisions, and we must know far more regarding the 

 lower Mammalia than we now do before such a course can be taken 

 with confidence. The reason for this is that save for a part of the 

 adductor magnus, little can be proved by the innervation, and it is 

 both simpler and more satisfactory to refer to a number of divisions 

 by number. In Zalophus I began at the most caudaul division and 

 Avorked craniad. (Figs. 11, 12, 13, 24.) 



Adductor 1 in the Zalophus was thin and arose from tlie caudal 

 border of the ischium betAveen the origins of the semimembranosus 

 anticus and quadratus femoris. It passed laterad to all the other 

 adductors to a fascial insei-tion over the medial tuberosity of the 

 tibia and onto a slight ridge extending along the distal border of the 

 medial condyle of the femur. 



Adductores 2 et 3 were apparently indivisible at origin, which was 

 along the caudal half of the pubis laterad of the symphysis and that 

 part of the ischial border that lay ventrad of the obturator foramen. 

 These two divisions were undoubtedly homologous with at least a part 

 of the true adductor magnus, for the femoral artery passed between 

 their insertional parts. At the middle of the muscle the more ventral 

 fibers separated into a ribbonlike slifD — adductor 2 — extending to a 

 ridge upon the medial condyle of the femur. The deeper part, consti- 

 tuting adductor 3, inserted upon a long, narrow area stretching over 

 the caudal surface of the femur from the distomedial greater tro- 

 chanter to a point upon the medial border of the shaft midway be- 

 tween the lesser trochanter and the condyle. On the bone this is indi- 

 cated by a barely perceptible ridge, corresponding to the usual linea 

 aspera. 



Adductor 4 was small and arose from the pubic border just craniad 

 of the origin of divisions 2 and 3. It passed deep (mediad) to both 

 of the last, broadened somcAvhat and inserted upon a slight ridge 

 extending over the caudal shaft of the femur from distad of the 

 middle of the greater to the lesser trochanter. 



Adductor 5 was also very narrow, arising along the pubic border 

 from the pectineo-psoas process to adductor 4. It passed superficial 

 (mediad) to all the other adductors in this area to a fascial inser- 

 tion over the medial epicondyle of the femur. This is the pectineus 

 of Murie. 



Adductor 6 arose from the pubis immediately deep to division 5, 

 and inserted narrowly upon the disto-lateral border of the lesser 

 trochanter. 



