MR. W. K. PARKER ON THE OSTEOLOGY OF BALiENICEPS REX. 333 



the Herons, being comparatively shorter and thicker than those of the more elongated 

 and feebler typical bird — viz., the Heron. There is a very thick but small hypo-para- 

 pophysis at the anterior part of the first dorsal in Baleeuiceps, but none in the others. 

 There are some rather large pneumatic foramina on the middle of the sides of the cen- 

 trums of the dorsals rather high up. The dorsal and pelvic ribs dilating below, form 

 at their tip a flattish articular surface for the hsemapophysis. The first of these ossified 

 ' sternal ribs ' is but little more than half an inch in length ; the fifth, which joins the 

 pelvic rib, is 2f inches long. These bones are broad above, narrow in the middle, and 

 then expand considerably from side to side to form the transverse synovial surface 

 for articulation with the sternum. 



In certain birds, several of the dorsal vertebrae become anchylosed together ; this is 

 seen in one group of the Raptores — the Falcons, but not in the other families. In 

 Falco peregrinus, subbuteo, (Esalon, and tinnunculus ; and (according to Professor Owen) 

 in the Australian Hawk {leracidea herigora), five of these joints are thus anchylosed, 

 one free vertebra intervening between these and the sacrum. The first of the five 

 coalesced bones has a floating rib, and belongs to the cervical region. The same 

 thing occurs in the Gallinse and Columbinse, but they have only four bones thus joined, 

 the first of which has floating (cervical) ribs. 



The Flamingo has the same structure as these latter birds, save that the ribs of the 

 first in the anchylosed piece reach the sternum by hasmapophyses. Of the six true 

 dorsals in the Agami {Psophia crepitans), the three first are anchylosed into one piece 

 as perfectly as in the fowls. Grus pavonina has distinct dorsals, but G. americana has 

 the second and third true dorsals combined into one bone. In the Grebes {Podiceps) 

 and in the Dab-chick {Sylbeocyclus europeeus) there are five true dorsals, the first four 

 of which are quite confluent ; this confluence in the latter bird afiecting the hypo-pa- 

 rapophyses as in the GallincB. These inferior median processes are in some birds 

 widely bifurcate. This may be best seen in the three first true dorsals of Colymbus 

 septentrionalis, and in the three last cervicals and first true dorsal of Alcedo ispida. 

 It is not, however, so common a character even as the confluence of the dorsal vertebrae ; 

 this latter state of the dorsal region being, after all, exceptional as to the entire class. 

 Another modification of the dorsal vertebrae has to be noticed ; — in birds with very 

 compressed dorsal centrums, as the Lapwing, or with compressed and carinate centrums, 

 as Parrots, Gannets, Cormorants, Pufiins, and also in the Penguin, where the centrums 

 are not so flat, the articulation of these elements is ' opisthoccelian.' This character of 

 an anterior ball and a posterior cup to the dorsal centrums is not found in the Pelican, 

 which, added to the strange modification of its jaws, and the highly pneumatic state of 

 its bones, make it very aberrant from the other Totipalmatae. There is no floating 

 abdominal hsemapophysis in the Balcsniceps — although this is very common in birds 

 (especially raptorial and insessorial species), it occurs however in the Adjutant. In 

 the skeleton of a Red-necked Grebe {Podiceps rubricollis) prepared by the writer, there 



VOL. IV. PART VII. 3 A 



