RHYNCHOPIN^, SKIMMERS. 713 



processes, and of the character of the depression for the nasal gland. The convex 

 borders of the fossie do not nearly approach each other on the median line, but are 

 widely separated. The fosste themselves are narrow and imperfect, not nearly contain- 

 ing the whole of the glands, which consequently project greatly over the edge of the 

 orbit. The fossa? are continued each as a well-marked groove, under the anteorbitiil 

 processes, tfceir ducts passing through a very large foramen on their way to the lining 

 membrane of the nose. The interortital septum is complete. The olfactory nerve 

 runs along in a furrow so deep as to be almost a canal. From the completeness of the 

 septum, between the orbits, the foramina of exit of the nerves at the posterior part of 

 the orbits are more perfect and less closely approximated than in the other subfamilies. 

 The conjoiuted bases of the sphenoid and ethmoid, Avhich form the inferior border of the 

 septum, and along which the palatal and vomerine bones slide, is much thicker and 

 stouter than ordinary, and does not extend nearly so far forward, nor has it an acute 

 apex nor deei^ly concave anterior edge. 



The forehead is exceedingly broad, and slopes down from the vertex at an unusually 

 great angle of descent. In its centre it is slightly concave laterally, owing to the de- 

 velopment and prominence of the anteorbital processes. Anterior to these it is i^erfectly 

 plane, wide, with parallel, straight sides, dipping down deeply with a square truncated 

 l3nse which forms, with the superior mandible, the very jjeculiar fronto-maxillary 

 suture. This " articulation " admits of a far greater degree of motion than exists in the 

 other subfamilies, and greatly exceeds that usually found among birds, excepting, of 

 course, the Fsiliaci. The connection between the bones of the cranium and superior 

 mandible is perfectly straight and transverse; very wide (being the whole width of 

 the broad frontal bone), and at the same time exceedingly thin and elastic. On the 

 superior surface of the suture there is a deep groove between the bones, a little wider 

 at either extremity than in the middle, but the under surface is quite smooth. The 

 osseo-cartilagiuous connective substance is pliable and elastic, so much so, that in an 

 old and dried preparation before me, the original mobility of the parts is in a great 

 measure retained. 



In the adult skull before me there are no discernible traces of any nasal bones, prop- 

 erly speaking ; but the suture is formed entirely by the apposed terminations of the 

 broad frontaJ, and eqi;ally broad mesial process of the intermaxillary. That portion 

 of bone usually known as the "maxillary" or descending process of tlie nasal, exists, 

 nuusually developed, and in an unusual position. Below it is firmly auchylosed and 

 completely consolidated with the mandibular ramus, just anterior to the malar anchy- 

 losis. From this base it extends upward and backward as a long, very slender, com- 

 pressed bone, running parallel with, but not touching the sides of, the osfrontis, to be 

 received by this thin, llat, laterally expanded termination into a slight depression in 

 the under and anterior edge of the ante-orbital process. As it particijjates in all the 

 movements of the upper jaw, its union with the ante-orbital processes is a movable 

 suture, of apparently the same general characters as the fronto-maxillary suture, of 

 which it is to be considered as really a part. 



The other elements Avhich assist to produce the movements of the upper jaw, are all 

 by their shape or position subservient to its increased mobility. The ossa pedicellata 

 are long and strong, and especially remarkable for the increased development of their 

 niakir eminences, wliich carry the ends of the zygomata far outward and downward, 

 and thus are enabled, with an ordinary degree of motion of the tympanic bones them- 

 selves, to impress upon the malar, and through them upon the superior maxillary bones, 

 an increased amount of motion. They also produce a somewhat peculiar shapes of the 

 articulatiiig surface for the inferior mandible. The orbital processes of the tympanic 

 bones are very short, small, and exceedingly acute. The, pterygoid bones present no 

 s)i(!cial i>eculiarities of shape, but, from the narrowness of the skull, are not so widely 

 divt'igent as in the other subfaiuilies. The palatal boues are remarkable for stout- 

 ness and widtli, and also for the solidity and extent of their anchylosis with the supe- 

 rior maxillaries. The outline of their posterior margins is very oblique, and they 

 tfrminate with quite prominent processes ibr the pterygo-palatal artuiilaticni. Poste- 

 riorly their inferior surfaces have considerable lateral concavity from the elevation of 

 their Viorders ; more anteriorly they are plane and smooth, their surlacf being directly 

 continuous with the plane of the nuixillaries. The vomer is shorter than usual, and 

 biliiicate to a less extent. The malai bones are perfectly straight ; their axes in a line 

 with the general iiielination of the axes of the mandibular processes of the intermax- 

 illary ; but just at their union with the maxillary bones there is a considerable angle 

 formed, from the increased divergence of the latter at that point. They are throughout 

 laterally comjiressed, except just at their anterior extremities, wliere they become hor- 

 izontally depressed and llattened, to give them the necessarj' mobility of elasticity in 

 an upward and downward direction. 



The interniaxillary bone is entirely peculiar in shape and general characters. It 

 is remaikable tor the i)re])ondeiaiiee in size of the mesial over the mandiltular pro- 

 cesses, and for the unusual extent to which the latter are united with the former 



