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Show 192 MR. A. H. GARROD ON THE [Feb. 1, length, and fusiform in general outline. The sacculating bands are not lateral, but on their outer and inner borders, being continued from the longitudinal fibres of the large and the small intestine. Their mucous membrane is not plicated when they are distended. It is only, among other birds, in Struthio and Rhea that the caeca are sacculated ; in these, however, there is only a spiral twist like that in the caecum of the hares and rabbits. Each caecum has a well-developed special sphincter muscle guarding its aperture of communication with the intestine; and what is more peculiar still is, that they do not open into the colon proper, but into a special cavity, a continuation of the main intestinal tube, but separated off by a very constricting sphincter from the colon, as well as by the ileo-caecal valve from the small intestine. This ileocolic cavity is f of an inch long and about \ an inch in diameter when undistended. Its mucous membrane is like that of the caeca, much more delicate than that of the colon. The ileo-caecal valve is a small slit-like opening, nearly \ of an inch long, with its lips projecting a little way into the ileo-colic cavity. The two openings of the caeca into the same cavity are one on each side of it, a little oblique in regard to it, and considerably larger in lumen. The opening into the colon is very constricted ; beyond it the mucous membrane of the large intestine is, as Dr. Crisp remarks*, transversely plicated, to produce an appearance much like coarse valvulae conniventes. Nothing like the above-described condition is to be observed in any other bird, not even in Struthio or Rhea, in both of which, as typically, the caeca enter the commencement of the uniformly cylindrical colon by fair-sized orifices, not surrounded by a special sphincter. This being the case, I cannot agree with Prof. Parker's remark *f that "there is nothing whatever in the digestive organs, which are extremely voluminous, to separate the bird from the Geese." Respiratory Organs.-Prof. Parker J remarks, " the trachea and inferior larynx are truly anserine ; for there are no inferior laryngeal muscles, the contractors of the trachea ending one third of an inch above the bifurcation, and only a delicate fan-shaped fascia going to the half-rings. Moreover the trachea itself, from being flat and cartilaginous, becomes round and then compressed, and osseous an inch above the bronchi, so that it cannot be mistaken for any other than the trachea of an anatine bird." In that the lower end of the trachea is of smaller diameter than is the tube higher up, in that in the same part the constituent rings are in close contact without scarcely any intervening membrane, in that there are two pairs of tracheal muscles running to the thoracic parietes, and in that the intrinsic lateral tracheal muscles end before they reach the bifurcation of the bronchi, the syrinx of the Screamers approaches that of some of the Anseres; but in that there is no special modification of the organ in the male, and in the absence of chondrification or ossification of what are generally present as dilating rings or half-rings * P. Z. S. 1864. p. 16. t P. Z. S. 1863, p. 514. \ Loc. cit. |