898 DR. R. W. 6HUIELDT ON THE OSTEOLOGY OF THE [DcC. 1, 



the essential characters of the basal aspect of tlie skull as found in 

 the typical Swifts are present in Panyptilu, and they perfectly agree 

 in most important points with the same characters as described by 

 Professor Huxley for Gypselus apus (figs. D and E). 



The vomer ( Vo) is long and narrow, being deeply cleft behind 

 where it straddles tlie rostrum of the sphenoid. Either limit is 

 carried back as far as the palatine head of the corresponding side, 

 with wiiich it firmly articulates, as well as with the initial portion 

 of its ascending process. Anteriorly, the vomer dilates into a 

 horizontal, triangular extremity, the line of the base being in front, 

 its angles just resting, one on eilher side, on the upper edges of the 

 broad maxillo-palatines, while the apex merges into the cleft portion 

 which extends backwards. 



A maocilln-palniine (Mivp) has the form of a spherical triangle, 

 is notably well develo[)ed, but does not meet its fellow in the median 

 line, the interval being s))anned by the vomer, as just described. 



The palatines (PI) are principally in two horizontal planes, and 

 either one has a very characteristic form in the Swifts, which is 

 nearly approached by the Swallows. Its inner margin is deeply 

 cleft, giving rise to an anteriorly directed process that is quite 

 striking in the Cypselidec, though it amounts to nothing more than 

 an exaggeration of a similar condition found in the Passeres. 



The narrow palatine body merges anteriorly into the premaxillary, 

 and as it passes forwards to do so, undcrlaps the great tuberous 

 antorbital ; while further on, it shuts out of sight from this view the 

 connection between the vomer and tlie maxillo-palatine. 



Another exaggeration of a Passerine character of the palatine, seen 

 in the Swifts, is the form assumed by the postero-external angle of 

 the bone. It is in them produced into a well-marked oblong process 

 directed backwards and outwards (see figs. D, E, and F). 



In the Passerine birds generally the palatines have but one point 

 where they come in contact, and this is at their heads under the ros- 

 trum, where they articulate with the pterygoids. This applies also 

 to the Swallows, while in Fanypfihi, and presumably in other Swifts, 

 these bones fail to meet even here, being sejiarated by quite an 

 appreciable interval (fig. D). We have already seen that they are 

 very widely separated in TrocJnlus at this point". 



A pterygoid (fig. D, ;;/) is a very long, slender, and straight rod of 

 bone, having the same essential characters and making the same style 

 of articulations with quadrate and palatine, as in the typical Passerine 

 birds. 



In most particulars of any importance, so far as the basis cranii, 

 the rostrum, ethmoid, and all other parts of the skull of Pamjptila 

 are concerned, they make no great departures from the generalized 

 Passerine skull, and they are by no means very different from such 

 characters as they are found in Ilirundo. Indeed, so far as t.his part 

 of the skeleton goes, my studies of the osteology of American Cijp- 

 selidcp and HirmidimdcB fully confirm Professor" Huxley's investiga- 

 tions in that direction, who long ago pointed out the close relation- 

 ship of these two groups of birds (P.Z.S. 18C7, p. 4.52). 



