3. The Pelargomorphæ.—" There are no basi-pterygoid processes, and the palatines usually unite for a greater or less distance behind the posterior narcs ; but they send down no vertical plate from their junction." In the Ardeidce they do not unite; in all these forms the coalesced part is short as compared with that of the Cormorants and Pelicans ; in both Scopus and Balceniceps the ankylosed part is carinate below (Trans. Zool. Soc., vol. iv. plate G5, fig. 1, pal.]. "The maxillo-palatines are large and spongy. The angle of the mandible is truncated," except in Platalea and Ibis. The vomer is smallish and cultrate in Ciconia nigra; larger by far, cultrate, and pedate at the end in Tkresciornis oethiopictit ; as large in Platalea l :ucorodia, but pointed in front and carinate below. Even in the last of these forms, in a half-grown individual, no sign of a median suture was seen. The vomer of Scopus is sharply cultrate above and rounded below ; it reaches beyond the maxillo-palatine mass. In Balccniceps (op. cit., p. 308, plate 65, fig. 1, v.) the vomer is like that of Scopus and Ciconia, but it is actually smaller than either. In most of these Ciconian and Ibidine types[1] the vomer is evidently azygous, but in all the skulls of Ardeidce now before the writer, viz., one or two species of each of the following genera, Ardea, Botaurus, Nycticorax, Garzetta, Tigrisoma, the vomer is double, large, and charadrian.
In Ardea dnerea the vomer is coalesced behind with the long, elegant, bicarinate palatines, and in front runs its point in between the free retrai lobes of the maxillo-palatines. The moieties have each a rounded keel, and those keels run parallel at first and then run into each other in front ; above, the two halves form a deep fossa, in which the sub-carinate parasphenoid glides. The edges of this trough are roughly tuberculated and turned over, like the rim of a cup ; the primary suture between the halves is retained behind for half the length of the bone. In several Ardeidce an additional maxillary bone the " post- maxillary " is formed behind the angle of the maxillary. It is small in Ardea garzetta and Botaurus slellaris, and of good size in Botaurus viridis and Nycticorax ardeola. This bone was first found by Mr Parker in the Emeu. In Tigrisoma leucolophum there is a pair of " inter- palatines," as in the Duck tribe. In the Pelagomorphce the charadrian type reaches its culmination ; yet the most exquisite forms, such as the Egrets and smaller Bitterns, and the most gigantic, as the Adjutant, are evidently specializa tions of a type similar to the pluvialine Schizognathcc.
4. The Dysporomorphæ.[2]—" The rostrum is long and pointed, and more or less curved ; and the external nasal apertures are very small. There are no basi-pterygoid pro cesses. The palate bones unite for a considerable distance behind the posterior nares, and send down a vertical crest at their junction. The maxillo-palatines are large and spongy. The angle of the mandible is truncated."
The inferior crest of the combined palatines is largest in Pclecanus , above, in Phalacrocorax and Sula, this plate is grooved for the sphenoidal rostrum, but in the Pelican there arises a huge crest, and the rostrum of the sphenoid rises rapidly out of its way. Here the secondary palatine arch has the same habit as the primary trabecular arch a modification constant in birds in the latter. All the parts in front of the very mobile cranio-facial hinge are molten together into one mass, and the nasal labyrinth is in its most aborted state.
In Phalacrocorax the perpendicular ethmoid is of small antero-postcrior extent. There is no presphenoid, but merely a small Y-shaped orbito-sphenoiclal band of bone above the optic passage. The same structure is seen in Himantopus and Eurypyga. In the Cormorant an oblong ossicle lies on the commencement of the zygoma. It is large in P. carbo, and small in P. c/racuhis. A still larger ossicle has heightened the zygoma in Sula alba. This is the " post-maxillary." In Sula alba the basi-temporals are as little developed as in the Dromccidce, less than in any other Carinate bird. Behind each moiety there is a largo oval opening, not far in front of the occipital condyle ; this exposes the loose diploe within. The small eustachian tubes open at a little distance from each other, in a wide shallow fossa, on the part where the three elements of the parasphenoid meet. In both the Pelican and the Cormo rant there is an elegant, crescentic, lipped, free margin to the very Ardeine basi-temporal plate. In Sula alba the columella auris is very long and bent. It has a small cartil aginous extra-supra-stapedial process, and a long attenuated cartilaginous infnx-stapeuial, terminated by a bony fusiform stylo-hyal. The hinge for the mandible is very far back in Sula, whose cranio-facial hinge almost rivals that of the Parrot and Toucan. In the Cormorant the mandibnlar articulation is almost carried as far back as in the Croco dile. In Sula alba the zygoma is very thick in front, and is suddenly reduced to an extremely thin bar, where it passes into the upper beak.
5. The Aetomorphæ.—<! The rostrum is more or less- arched and hooked at the tip. Basi-pterygoid processes may be present or absent. The maxillo-palatine processes may be concavo-convex lamellse, or may be spongy and fill up the base of the rostrum ; but they are always [except in Dicholophus, a genus which the writer adds to the group] united with an ossification of the septum. The breadth of the articular surface at the distal end of the quadrate bone is greater than its length, the outer condyle extending about as far downwards as the inner. * This is best seen in the Cariama (Dicholophus), and in the Owls, Hawks, and Falcons ; in the larger Old World Vultures (e.g., Gyps fulvus) it is not so well seen. " The angle of the mandible is never recurved." At pp. 441 and 442 op. cit. it is stated that "the maxillo-palatines unite with one another and with the extremity of an ossified septum, so as to fill up the maxillo-palatine valley." In the carefully prepared specimens before the writer, it is found that there is a space between the right and left maxillo- palatine, not only in the Cathartidce, where it is evident, but also in Gypogeranus, where it is least. Intermediate between these types come the Old World Vultures and the Eagles. The skulls at hand give the following results, viz.:—
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a. Perfect indirect Desmognathisni. Sarcorhamphus papa, Aquila (sp. pi., including Hdotarsus- ecaudatus), Gyps fuhus, Neophron pcrcnopterns, Asio otus, Asia accipitrinus, Aluco jlammciis, Kctupa ccylonica, Athene noclua, Strix slridula, Elanus cccndcus. b. Imperfect direct Dcsmognathism. Dicliolophus crislatus. c. Perfect direct Desmognathisni. Falco 2>crcgrinus, Falco tinnunciuus, <alco cesalon, Accipitcr nisus, Butco vulgaris, Circus cyancus, Haliaslur indus.
most aborted in DicJiolophus, Hdotarsus, and G>jps. They reappear as aborted prickles or knobs in some Eagles, in Neophron, Elanus, Circus, and Accipitcr, and in the young: of these they are rather large. In Haliastur indus they are- large, rounded flaps, with no cartilage on their end. Then come Gijpogeranus, the Cathartidce, and the Owls, in which they are constant. In all the Owls, as in Pigeons and some of the Turnicidce (see Trans. Zool. Soc., vol. v. plate 34, fig. 2, m.o.f.), the slow growth of the occipital region of the chondro-cranium leaves a membranous space,
over the foramen magnum. This is not, or is very rarely