There are other peculiarities that unite these birds, which will be found mentioned on p. 183. The third group, containing the hornbills and hoopoos, may be thus defined : Group C.-Oil gland feathered; fifth remex present. Muscle formula, AXY. No expansor secundariorum. Cæca absent. Skull desmognathous. The colies are the only birds among the Anomalogonatæ besides the Caprimulgida which possess the biceps slip; there is a rudiment of this structure in Bucorvus. The remaining families are treated of separately and need not be defined here. This arrangement, nearly coincident with that of GADOW, is widely different from that of GARROD and FORBES. The former divided the birds (excl. Striges) into the three groups of Piciformes, Passeriformes, and Cypseliformes. They were thus defined : Piciformes.-Oil gland tufted; cæca absent; external branch of pectoral tract given off at commencement of breast. Muscle formula, (A)XY. Picidæ, Capitonidæ, Upupidæ, Bucerotida, Coliidæ, Alcedinidæ, Momotidæ. Passeriformes.-Oil gland nude; cæca present; pectoral tract simple or with external branch given off beyond middle of breast. Muscle formula, AX(Y). Passeres, Bucconidæ (?), Galbulidæ, Coraciida, Meropidæ, Trogonidæ. Cypseliformes.-Oil gland nude; cæca absent. Muscle formula, A. To these FORBES added a fourth group Todiformes, on account of its having at once cæca and a tufted oil gland. This latter group was regarded by him as most nearly representing the ancestral anomalogonatous bird. PASSERES Definition.-Oil gland nude. by odontoid process. Skull ægithognathous. Atlas perforated This is an enormous group of birds, numbering over 6,000 species, which are spread over the entire globe. As a rule they are of small or moderate size; but some large species, such as the raven and other Corvida, are included in the assemblage. In spite of the numerous species and of a certain amount of differentiation in external form, the group is structurally a uniform one, the difference being in characters which have not as a rule been regarded as of primary importance. In all Passeres the foot has this structure: the first toe is directed backwards, and none of the other toes are ever changed in position. Cholornis is exceptional in that the fourth toe is abortive. GARROD noted, some years since, another peculiar character of the group, which may possibly be universal, with the exception of Menura and Atrichia. This concerns the arrangement of the tendon of the patagialis brevis; and the passerine disposition may be understood from a comparison of the two descriptions. In the passerine the tendon of the muscle does not end upon the tendon of the extensor, as it does in the picarian bird, but, though attached to it firmly, retains its independence and runs back to be attached near it to the extensor condyle of the radius. This difference, though small, appears to be constant to the Passeres. Another character dealt with on p. 41 of the present work may be also an exclusively passerine character. In birds belonging to the present family the oblique septa, instead of having a separate attachment to the sternum, are either not attached In a specimen of Gracula intermedia the cæca were as long as half an inch, an exceptional length. Very rarely AX-. at all, lying loosely over the liver, or have but one attachment, which they share with the falciform ligament. It is very general-but there are a few exceptions, which will be dealt with later-for the sternum to have a forked manubrium in front and a single pair of notches behind. The number of rectrices present among passerine birds varies. They are, indeed, completely absent in wrens of the genus Pnoepyga. Twelve is the usual number, but ten only occur in Xenicus, Phrenotrix, and Edolius, while Menura superba has sixteen. The aftershaft is 'very weak and downy when present, and is sometimes (e.g. Paradisea rubra) absent altogether. As to the pterylosis, we may take Ampelis cedrorum, recently described by SHUFELDT,' as an example of passerine pterylosis, mentioning afterwards such variations from this type as are met with. In the bird in question the dorsal tract is exceedingly narrow from the origin in the fairly continuous feathering of the head down to a point in the pelvic region, where it is greatly dilated to form a diamond-shaped area; this again contracts to the original dimensions, and the tract concludes a little way in front of the base of the oil gland. From the lateral angles of the diamond-shaped area a tract runs to the feathering of the legs. On either side of the oil gland arises a short tract, which does not leave the trunk, but appears to be the hinder part of the femoral tract of some other birds. It is perhaps noteworthy that it is very similar to the corresponding one of the Bucconidæ and Capitonidæ, also, however, of the kingfishers. The ventral tract divides early on the neck, and on the breast is increased in breadth, the outer rows of feathers being much stronger than the inner set; the latter (not the former) are continued down to the cloacal orifice, which they completely surround by a narrowish band of feathers. The humeral tracts, which are strong, are connected with the head feathering by a special neck band as wide as the dorsal tract. NITZSCH does not figure this connection or that of the diamond-shaped dorsal area of feathers with the In a paper dealing with Macrochires in J. Linn. Soc. vol. xx. femoral feathering; but apart from this the same type of pterylosis occurs in many types, such as Motacilla, Certhia, Oriolus, &c. The principal variation is offered by those passerines in which the spinal widened area is not solid, but encloses a space. We find this in Coracina cephaloptera and Seleucides. In others (e.g. Eurylamus) there is the same ephippial space within the dorsal tract, but the posterior sides of the diamondshaped space are formed by a single row of feathers, which contrast with the mass of feathers which form the anterolateral boundaries of the space. This arrangement culminates in, for example, Hirundo and Diphyllodes, where the dorsal tract forks, and there is no connection between the ends of the fork and the single posterior part of the spinal tract.' The skull of Passeres has been mainly investigated by PARKER and by SHUFELDT.2 Corvus may be taken as a type, and the divergences therefrom noted later. As are all passerines, it is ægithognathous; the maxillo-palatines extend obliquely outwards and backwards; they approach each other in the middle line, and expand over the vomer. The vomer is broad and bifurcate both anteriorly and posteriorly; from the anterior horns a small separate piece of bone goes For passerine pterylosis, see, in addition to NITZSCH, GIEBEL, On Pterylosis of Paradisea,' Zeitschr. f. d. ges. Naturw. xlix. p. 143, and for Philepitta ibid. p. 490; SHUFELDT has described Chamaa, Journ. Morph. iii. 1889, p. 475; HELLMANN, Beitrag zur Ptilographie u. Anatomie der Hirundo rustica,' J. f. O. iv. 1856, p. 360; GADOw, 'Remarks on the Structure of Certain Hawaian Birds,' in WILSON and EVANS's Aves Hawaienses, ii. Sept. 1891. 2 For osteology of Passeres see PARKER, On the Structure and Development of the Crow's Skull,' Month. Micr. Journ. 1872, p. 217; On the Development of the Skull in the Tit and Sparrow Hawk,' ibid. 1873, pp. 6, 45; On the Development of the Skull in the Genus Turdus,' ibid. 1873, p. 102; On Egithognathous Birds,' Trans. Zool. Soc. ix. p. 289, x. p. 251; MURIE, ‘On the Skeleton and Lineage of Fregilupus,' P. Z. S. 1874, p. 474. LUCAS, Notes on the Osteology of the Thrushes,' &c., P. U. S. Nat. Mus. xi. 1888, p. 173. SHUFELDT, Osteology of Eremophila,' Bull. U. S. Geol. Surv. vi. p. 119 ; 'Osteology of Lanius,' ibid. p. 351; On the Skeleton in the Genus Stur nella,' &c., J. Anat. Phys. xxii. p. 309; 'Osteology of Habia Auk,' v. p. 438 ; Osteological Notes on Puffins and Ravens,' ibid. p. 328; GIEBEL, Zur Osteologie d. Gattung Ocypterus,' Zeitschr. f. d. ges. Naturw. xxi. p. 140. on each side to the maxillo-palatines. These are the septomaxillaries of PARKER, and appear to remain perfectly distinct in Corvus cornix, but not in Corvus frugilegus. There are no basipterygoid processes; the pterygoids have a long foot-like attachment (as long as the free part of the bone) not only to the palatines, but to the interorbital septum also. The nares are holorhinal and pervious. In Corvus cornix the lacrymals reach the jugal bar; there is practically no orbital portion, the descending limb being closely attached to, but not fused with, the broad and thick ectethmoid. The mandibular rami have a large oval perforation near to the articular surface. Among genera nearly related to the Corvidæ are various slight modifications of skull structure. In Manucodia, for instance, the rostrum is broadly ossified and fused with the co-ossified palatal plates of the maxillæ. The nasal septum is complete, and the conjoined ectethmoids and lacrymals are enormously swollen. In Ptilonorhynchus violaceus the ectethmoids and lacrymals are separate, though in contact; contrary to what is found in Corvus, it is the latter and not the former which border the orbit above. The palatal conditions of Manucodia are repeated and emphasised in Gymnorhina and Strepera. There is a firm union across the middle line in front of the vomer, with which, indeed, the anterior horns of the vomer are ossified in Strepera. In both birds, moreover, the pterygoids are fused with the palatines, and the nostrils are partly obliterated by bony growth. The desmognathism' thus produced in the crows of 'Notogæa' is not limited to that family. In Pheucticus and in Cracticus cassicus there is the same state of affairs. Other features in which the passerine skull shows variations are the maxillo-palatines, vomer, and pterygoids; in Gracula javanensis, for example, the pterygoid has a very limited area of articulation with the palatine; there is no expanded foot, as in crows, &c.; the maxillo-palatines are very long and slender, actually reaching the inner plate of the palatines. The vomer is narrow in the body, though the two anterior 'cornua' are thick. Trochalopteron is almost desmognathous |