REPORT ON THE ANATOMY OF THE PETRELS. 21 



Iii Pelecanoides (fig. 6) the tongue is fleshy, and fairly parallel-sided, tapering 

 apically. It is but little free, and occupies most of the interspace between the mandi- 

 bular rami. Its base is notched, and provided with some largish spines, which continue 

 forwards for about the basal half, or more, of the lateral margins. On the dorsal surface 

 there is alway a peculiar lanceolate mark, apparently due to a difference in the nature of 

 the mucous membrane covering the tongue over this area. 



The oesophagus — which in the Albatrosses, as already described by Pavesi, may be 

 surrounded at its commencement with a zone of spines, continuous below with the spines 

 covering the laryngeal eminence — is always capacious and distensile, but possesses no 

 crop. Inferiorly, in the thorax, it passes without any marked constriction or other 

 difference into an enormous proventriculus, which is a thin-walled bag, reaching down 

 nearly to the posterior extremity of the abdominal cavity, which it largely occupies, 

 lying to the left side of the stomach proper and the mass of the intestines. This great 

 proventricular bag is twisted back on itself apically, and then, becoming slightly narrower, 

 passes by a small aperture into the stomach proper or gizzard. This aperture is there- 

 fore to the right of, and anterior to, the great " fundus," which lies freely in the posterior 

 part of the abdominal cavity, covering there the terminal portion of the intestine and 

 cloaca. Internally, the proventricular glands are seen to cover pretty uniformly the 

 whole surface of the mucous membrane, with the exception of a more or less narrow 

 zone, which lies between this glandular part and the stomach proper, correspond- 

 ing pretty nearly to the narrower, ascending part of the bag as seen from outside (vide 

 PI. II. figs. 1 and 2). The extent of this very deep "zonary" proventriculus (pr.) is 

 always very considerable in the Petrels, being of course, cceteris pa/ribus, larger in the 

 larger than in the smaller species. In Majaqaeus its extent is 4*0 inches ; in Pelecanoides, 

 1/85 inches : in Fregetta grallaria, 1*2 inches. 



The stomach proper (g.) is always small and more or less globular, with fairly muscular 

 walls and provided with the usual central tendinous sheets, so that it may fairly be called a 

 gizzard. Its situation is peculiar, lying always above and to the right of the proven- 

 tricular fundus, and with its pyloric part so flexed on itself that it looks backwards 

 instead of forwards as in all ordinary birds (vide PI. II. figs 1, 2), in this respect 

 somewhat resembling the stomach of Strathio. In Struthio, however, the pyloric aper- 

 ture is on the deep (dorsal) side of the stomach, nearly in the middle line, and so concealed 

 when the viscera are viewed from the abdominal aspect. In the Tubinares the pyloric 

 aperture, on the other hand, is quite superficial, lying at the inferior (posterior) end of 

 the gizzard in the angle formed by the two parts of the bent proventriculus. 



The gizzard, which is nearly always found full of the horny beaks of Cephcdopoda, is 

 fined internally by an " epithelium," which is usually dark in colour, and frequently of 

 almost corneous texture, with a more or less corrugated or wrinkled free surface (vide 

 PI. II. fig. 4, where the epithelial lining of the everted gizzard of Fidmarus 



