1 ShufeI-DT, Osteolo(;y nf Harris's Cormorant. 



lOI 



^generations, been entireU' lost, and tlu- wings have become 

 reduced to mere secondary aids to locomotion under water.* 



At this writing, there are five practically perfect sterna of this 

 flightless Cormorant before me ; and, while they all offer essentially 

 the same characters, there are, nevertheless, some very interesting 

 differences to be seen among them upon comparison. 



To be explained in one way or another, these sterna may. in 

 the first place, differ markedly in size. For example, in all of 

 them the costal processes are large, drawn out into a somewhat 

 acute triangular form, and tipped off with a little bony nib. These 

 nibs are good points from which to measure the extreme trans- 

 verse width of the bone, and this width in No. 19,721 equals 

 84 millimeters, while in No. 19,628 it but equals 74 miUimeters, 

 and in No. 19,722 rather more, or 78 mm. Again, No. 19,721 

 has an extreme mid-longitudinal length of 89 mm. ; in 19,628 

 this is again much less in comparison, equalling but 72 miUi- 

 meters, and so on for the rest. In other words, whatever may 

 be the actual size of the sternum, with respect to width and 

 length, the fact remains that in its form it is nearly square in 

 outUne. It is also much flattened out from above, downwards, 

 the general concavity of its ventral side not being as profound 

 as in most all other Cormorants, as in, for example, P. auritns, 

 P. nrile, and P. carbo. 



I find no exception to there being four large facets on either 

 costal border whereon the haemapophyses or " costal ribs " 

 articulate. There are no pneumatic foramina among these — 

 that is, in the oblong concavities separating them, or in the 

 triangular one anterior to the leading facet or behind the last 

 one ; in fact, the sternum of Nannoptertim harrisi is a non- 

 pneumatic bone, like nearly all. if not all, of the rest of its skeleton. 

 Some of the species in the genus Phalacrocorax have a pneuma.tic 

 sternum, but not every one of them. It enjoys that condition 

 in P. auritns, but not in P. nrile, and so on. 



The keel or carina of the sternum in Harris's Cormorant has 

 become reduced to a mere rudiment of what that part of the bone is 

 in those species of the PhalacrocoracidcB that fully possess the power 

 of flight (see fig. 7, Plate XVI. ; fig. 16, Plate XVII. : and fig. 19, 

 Plate XVIII.) Anteriorly, the " carinal angle " is still preserved 

 and enlarged for its articulation with the os furcula, while but a 

 remnant of the keel itself remains. This last is concaved upon 

 either side, and in some specimens this concaving is so profound 



* Dr. Gadow, in a few forceful words, refers to what the skeleton of 

 NdHHopterum should teach us when he says that " .\n important and stern 

 lesson, taught by this flightless Cormorant, a first-rate swimmer, is, of 

 course, its analogy with Hesperornis. which, in spite of all that has been 

 said about its structure and affinities by Furbringer and myself, occasionally 

 still figures as a member of the RatitcB. He has no keel, therefore he is a 

 Ratite. Fiat jnstitici, pcreat common-sense!" (lac. cii.. p. 173). It occurs 

 to me that there were still others who very materially assisted in eradicating 

 the erroneous notion that Hesperornis was some sort of a " swimming 

 Ostrich" — Professor D'Arcy W. Thompson, for instance. 



