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Show 1870.] ON THE OESOPHAGUS OF SAUROPSIDA. 283 vated. As I have not made an examination of the osteology of these birds, I will merely point out that there is a remarkable osteological difference in the orbit of Dacelo from that of Alcedo and Ceryle, which is at once apparent on removing the skin from the crown of the head, the lachrymal bone in the former bird attaining the development so characteristic of the Falconidae and Strigidae, in which it contributes to roof-in the eye. DESCRIPTION OF PLATE XXIV. Fig. 1. Muscles of* back of neck of Ceryle stellata : a, a', upper and lower bellies of biventer cervicis (aponeurotic sheath removed on each side); *, transverse tendon ; b, longus colli posticus ; c, complexus. 2. Muscles of back of neck of Dacelo gigas: a, a', upper and lower bellies of biventer cervicis; b, aponeurotic sheath retained on left side; c, trapezius ; d d, latissimus dorsi. 3. Muscles at back of neck of Alcedo ispida: a, a', upper and lower bellies of biventer cervicis (aponeurotic sheath removed). 4. Viscera of Dacelo: a, trachea; b, bronchus; c, gland ; d, oesophagus; e, lymphatic gland; /, heart; g, liver; h, stomach; i, convolutions of intestine; k, cloaca. 5. Oil-gland of Dacelo gigas. 6. Oil-gland of Alcedo ispida. 7. Orbit of Dacelo: I, lachrymal. 8. Orbit of Alcedo: I, lachrymal. 2. On the Taxonomic Characters afforded by the Muscular Sheath of the (Esophagus as regards Sauropsida and other Vertebrata. By G E O R G E G U L L I V E R , F.R.S. This paper is intended to show that the subject of it deserves more attention than it has yet received ; to which end some of the results of ni)** observations will be briefly noticed, referring for more particulars to m y descriptions in the ' Proceedings of the Zoological Society' for September 10, 1839, June 14, 1842, and April 22, 1869. And if, by now again calling attention to the question, it should receive such additional investigations as may lead to a more accurate and extensive knowledge of the taxonomic value of the oesophageal sheath, the object of the present communication will be attained. Although more than a quarter of a century has passed since the observations above cited proved that either the comparative distribution, or presence, or absence, of the transversely striped muscular fibre of the oesophagus may afford good diagnostics between certain large groups and subsections of Vertebrates, and Leydig has confirmed m y results as to the deficiency of this fibre in the oesophageal sheath of Sauropsida, these facts have not yet been entertained in the books of systematic zoology and comparative anatomy. This neglect may have been caused by the complete investigation of the subject being somewhat tedious, requiring extensive examinations with good instruments, and relating to morphological arrange- |