CAPRIMULGI

Definition.-Anisodactyle. Oil gland nude.' Rectrices, ten. Aquintocubital. Aftershaft present. Skull holorhinal. Both carotids Caca large. Ambiens and accessory femorocaudal absent. Deep flexor tendons of type V.

present.

This group of birds shows a considerable amount of structural variation, which allows of the separation of the genera into at least two families; they are, however, all united by the characters in the above definition. The

FIG. 109.-LEFT FEET OF Antrostomus
vociferus (RIGHT-HAND FIG.) AND
Nyctidromus albicollis (AFTER
SCLATER).

FIG. 110.-RIGHT FOOT OF Podar. gus Cuvieri (AFTER SCLATER).

external aspect too of these birds, with the widely gaping mouth and their generally softly tinted grey and brown plumage, enables them to be readily distinguished from other

groups.

1 Sometimes said to be absent in Podargidæ, but FÜRBRINGER found it in Batrachostomus.

2 Absent in Egotheles,

In the typical Caprimulgida (fig. 109) the claw of the middle toe is serrated and the fourth toe has but four phalanges. There is no serration and five phalanges in others.' The aftershaft is present; in the aberrant Steatornis it is

not absent (as GARROD asserted). Podargus is remarkable for the possession of powder-down patches, of which there are two, one on either side of the rump (see fig. 111), first discovered by Mr. SCLATER. The patches of this bird are well defined and very compact, and have not the diffuse character that is seen in, for example, Rhinochetus. Powder downs are also found in Batrachostomus and Nyctibius.

'SCLATER, 'Notes upon the American Caprimulgidæ,' P. Z. S. 1866, p. 120. 2. Additional Notes on the Caprimulgidæ,' ibid. p. 581.

pterylosis has been elaborately described by GARROD for Steatornis; so we shall select that bird, though it is, as

FIG. 112.-PTERYLOSIS OF Steatornis (AFTER GARROD).

THE RIGHT-HAND FIGURE REPRESENTS THE DORSAL VIEW; THE LEFT, VENTRAL.

For notes on Steatornis see, in addition to papers quoted, N. FUNCK, 'Notice sur le Steatornis caripensis,' Bull. Ac. Belg. 1844, p. 371; F. STOLZMANN, Observations sur le Steatornis Péruvien,' Bull. Soc. Zool. France, v. 1880, p. 198; HUMBOLDT, Sur le Steatornis,' Bull. Soc. Philom. 1817, p. 51;

already hinted, in many ways an aberrant form as a type. The dorsal tract (see fig. 112) gradually narrows as it passes down the neck, but the feathers get stronger; it bifurcates between the scapula to form a well-defined fork, which ends ultimately, having become weaker. Between this fork, and not connected with the rest of the dorsal tract, appears a spear-headed patch of feathers. The shaft' of the spear' becomes stronger as it descends to end abruptly at the base of the oil gland. The ventral tract is narrow between the mandibles; it is undivided upon the neck. At the beginning of the breast it divides into a wide outer and a narrow inner portion, the latter being more strongly feathered. The two converge on each side towards the cloacal aperture, but do not reunite.

In Caprimulgus, on the other hand, the ventral tract bifurcates in the neck, and the two ventral tracts are single, and there is no such abrupt break between the two parts of the dorsal tract as has been described above in Steatornis. Nor is there in Antrostomus, where there is no narrowing of the posterior part of the dorsal tract. Nyctidromus is much the same.'

The tongue in the goatsuckers is more or less abortive; in Podargus it is a curious tough but transparent membranous organ.

As mentioned in the definition of the group the caca are large; but as a unique exception Egotheles seems to be entirely without them. In all the genera the left lobe of the liver is rather the smaller; and all, save Chordeiles, have a gall bladder. The intestinal measurements in inches are given on the following page.

The intestine (according to MITCHELL) is primitive and owl-like, while the caca are dilated apically, as in owls.

J. MURIE, Fragmentary Notes on the Guacharo, or Oil Bird,' Ibis (3), iii. p. 81 ; L'HERMINIER, Mémoire sur le Guacharo,' Nouv. Ann. Mus. iii. 1834, p. 321, and note Sur la Classification Méthodique du Guacharo,' &c., Rev. Mag. Zool. (2), i. p. 321; J. MÜLLER, Ueber die Anatomie des Steatornis caripensis,' M.B. k. Ahad, Wiss. Berlin, 1841, p. 172, and Anatomische Bemerkungen über den Guacharo,' Arch. f. Anat. u. Phys. 1842, p. 1.

1 For further details of feathering See CLARK, The Pterylography of certain American Goatsuckers and Owls,' Proc. U. S. Nat. Mus. xvii. 551.

The syrinx is highly characteristic in the Caprimulgi, Like the nearly related (?) cuckoos, we have both the tracheo-bronchial and the purely bronchial syrinx. Indeed, the stages are almost identical in the two groups. Cuculus and Caprimulgus correspond with a tracheo-bronchial syrinx; then we have Centropus and Podargus, and finally the culmination in Crotophaga and Steatornis of a syrinx furnished with a membrana tympaniformis, which does not commence until many rings below the bifurcation of the tube, the intrinsic muscles being attached to the first ring which borders upon it. It will be necessary to describe the various syringes in some detail; they have been studied and figured by myself. In Nyctidromus albicollis, which will serve as a type of the tracheo-bronchial syrinx which exists in the Caprimulgidæ (s.s.), the last four tracheal rings are closely applied in contradistinction to the preceding, which are separated by copious membranous intervals. The last two tracheal and the first five bronchial semi-rings are ossified. To the first of the latter are attached the intrinsic muscles. In Batrachostomus we have the intermediate type of syrinx, which may, however, be called bronchial. The first six bronchial semi-rings and the last three tracheal are ossified,

FIG. 113.-SYRINX OF Nyctidromus albicollis (AFTER BEDDARD).

On the Syrinx and other Points in the Anatomy of the Caprimulgidæ,' P. Z. S. 1886, p. 147.