AVIAN OSTEOLOGY. 401 



however, in this particular individual, has completely lost the 

 foraminal passage, while otherwise the morphology is quite the 

 same. 



One of the most interesting forms of the patella among 

 Cormorants is found in Phcdacrocorax vigua (figs. 12 & 13) ; for 

 it is not only very small and chunky, but the facet on its 

 infero-anterior aspect for the tibio-tarsus is relatively, as well as 

 actually, large. On the inner aspect, the big foraminal opening 

 is situated at the base of a fossa, as in Rannoj^terum harrisi, 

 while on the external side it is small again, and has, leading 

 down from it to the lower border of the bone, a deep gi'oove, 

 which not only indicates the suture between the two elements 

 composing this bone, but apparently the continuation of the 

 groove for the ambieiis as well. 



Passing to Phalacrocorax auritus (ISTo. 19262), the patella of 

 which species is shown upon two views in figs. 14 & 15, we find 

 that that sesamoid is rather small for a Cormorant of its size. 

 In it, the foraminal passage has gone entirely, while the bone, 

 upon the other hand, shows better than any other Cormorant's 

 patella I have examined, the two parts of which it is composed. 

 These are very plainly to be seen in the figures, — indeed, equally 

 as well as in the specimens themselves. 



There is a large patella in Phalacrocorax alhiventris (No. 18437, 

 figs. 16 & 17), where again we find, in the adult bird, the 

 foraminal passage almost obliterated, having been reduced to a 

 capillary calibre throughout. Sutural traces between the bone 

 are faint, while anteriorly the rotular excavation is broad and 

 deep, being but slightly wider at the top than it is at the distal 

 border. 



A most instructive patella is found in Phalacrocorax pelagicus 

 (No. 19032, figs. 18 & 19). Once more we find the foraminal 

 passage reduced to a very small calibre, though the entrances on 

 the inner and outer surfaces of the bone are still in evidence, 

 though very small. What is to be specially noted among other 

 things is, however, the position of the foraminal aperture on 

 the inner aspect (fig. 18); this is but 4 millimetres from the 

 posterior margin of the patella, while it is 9 millimetres from 

 the anterior margin, which is sufiicient to render the theory of 

 the "anterior" groove being filled in by an ossified fibrous liga- 

 mient — ridiculous. 



In its amalgamation and coossification of its parts, this patella 

 became to a large degree twisted, — a twisting that cannot well 

 be appreciated in the figures. Still, the bone fits most accurately 

 on the superior border of the cnemial process of the tibio-tarsus, — ■ 

 its lower border, antero-posteriorly, being no thicker than is that 

 of the leg-bone, while everything in its morphology plainly 

 indicates its origin. On the front of the patella, the rotular 

 channel is somewhat shallower than usual, and is as bi"oad above 

 as it is below, where it, in all particulars, directly continues the 

 corresponding channel separating the pro- and ectocnemial 

 apophyses of the tibio-tarsus. 



