330 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUiM. 



tions it resembles the patella in Podiceps. It differs materially, how- 

 ever, iu being perforated by a large foramen for the tendon of the am- 

 bicus muscle, agreeing in this respect with the patella of the Gannet 

 {Sula hassana, Briss.). The patella is much compressed transversely. 

 Seen from side to side it is triangular in outline, and the outer surface 

 is concave. AVhen in position, its longer axis was nearly parallel with 

 the axis of the tibia. Its lower extremity bears a large twisted articu- 

 lar face for the union with the femur, and the lower posterior half of 

 the inner side is toughened for attachment to the cnemial spine. The 

 position of the patella in the skeleton is shown in Plate XX. When 

 at rest, it extended iu front of the anterior margin of the ilium, and, 

 by its muscular attachments, added greatly to the power of the poste- 

 rior limbs in swimming. The superior extremity is obtusely pointed, 

 and the outer margin is arcuate." (Marsh, Odoutornithes, p. 93.) 



In jS^o. 41 of Science, I presented a lateral view of the leg-bones of a 

 Cormorant (Phalacrocorax), showing the form of the -patella in these 



-Fi 



Fig. 7. — Phalacrocorax hicristatus, seen from in front. Life size. Letters signify the same as in 

 the other illustrations. By the author. 



birds. The same specimen is given here ; only an anterior view is chosen 

 instead of the lateral one. 



This form is a particularly interesting one, and I am not aware of any 

 bird at present that can show a similar condition of the parts in ques- 

 tion. 



On the face of it, it almost looks as if a patella had developed of a 

 size equal to the rotular process, and subsequently the two became 

 thoroughly united, and formed one large patella, articulating as shown 

 in the drawings I have made of it. I do not say that this is actually the 

 case, nor were the young of this specimen, which also belong to the col- 

 lections at the Smithsonian Institution, of a projjer age to determine 

 exactly the manner in which this great bulky patella was developed. 



Some of the problems that are presented in the evolution of this sesa- 

 moid no doubt will be found to be very interesting and instructive. 



