AVIAN OSTEOLOGY. 395 



Personally I have not examined the patella in Hesperornis with 

 the view of substantiating Marsh's statement that it is "perforated 

 by a large foramen for the tendon of the ambiens muscle, agreeing 

 in this respect with the patella of the Gannet [iSala bassana 

 Briss.)." His several figures of the patella of Hesperornis regalis 

 do not show this " large foramen " (' Odontornithes,' p. 23, 

 plates XV. and xx. figs. 1-3), while I have yet to see the patella 

 of Sulci bassana presenting any such perforation for the ambiens 

 muscle as Marsh describes. 



However this may be, the fact remains that very radical dif- 

 ferences exist with respect to the fate and disposition of the 

 patella and cnemial process of the tibio-tarsus in Grebes, Loons, 

 Hesperornis, Penguins, Gannets, Cormorants, and many other 

 different species of water birds. Great differences also exist in 

 the morphology of this sesamoid and the aforesaid apophysis. 



This brings us to a point where the patella of the Phalacro- 

 coracidaj may be discussed. For this purpose I have befoi-e me 

 the skeletons of several species of Cormorants, all belonging to 

 the Collection of the U.S. National Museum, to whicli institution 

 I am indebted for the loan of them. It will not be necessary to 

 name these species here or to give their museum numbers, as this 

 information is fully set forth in the explanation of Plate LXI., 

 which appears at the end of this article. As to the 19 figures on 

 the plate, they are reproduced, natural size, from my own grouping 

 and photograph, — the latter having been made direct fiom the 

 specimens. 



Among avian osteologists the general opinion has prevailed that 

 the patella in Cormorants is a big trihedral one, in some way 

 " perforated " for the ambiens muscle, 



Garrod found the ambiens muscle present in the family Phala- 

 crocoracidfe ; and, in noting that Meckel had not done so, he states 

 that " it is peculiar in that [in the Cormorant] it runs through 

 the substance of the large triangular patella, in a bony canal"*. 



In another paper this gifted ornithotomist is still more positive, 

 and in speaking of the " Steganopods," he says : " The ambiens is 

 of fair size ; it deeply grooves the large ossified patella ; and some 

 of the fibrous ligament ovei'lapping this groove shows traces of 

 ossification ; so that in aged birds the groove may be converted 

 into a foramen, as is always the case in Phalacrocorax, where the 



made thereon. There is a curious slip in this paper with respect to the description of 

 tlie patella of the Gannet {Sula bassana). On page 362 I state that " Professor Marsh 

 tells us that the patella of Szila is perforated by a large foramen for the passage of 

 the tendon of the ambiens muscle." On pages 329 and 330 1 quote the entii e para- 

 graph from Marsh's ' Odontornithes ' (p. 93) wliere he gives this description of the 

 patella of Szila and states on page 327 that " I fail to find any such foramen in the 

 patella of the specimen of Sula before me, although it has a shallow, oblique groove 

 across its anterior face that seems to correspond with the one described when speaking 

 of the patella of the Penguin." This statement is supported by a con'ect figure of 

 the patella in Sula bassana (No. 16643, Coll. U.S. Nat. Mus.), and I must believe 

 that the description left us by Prof. Marsh is another of those curious slips of his in 

 the osteology of modern birds. 



* Garrod, A. H. " On Certain Muscles of the Thigh of Bird:--, and on their value 

 in Classification," Pt. 1. P. Z. S. 1873, pp. 636, 637 (footnote). 



