216 ON THE HABITS OF THE DARTER. 



P. z. 8.1881, 37. NOTE ON MR. BARTLETT'S COMMUNICATION ON 

 P- m THE HABITS OF THE DARTER.* 



THE specimen put into my hands by Mr. Bartlett is a somewhat broken 

 bag-like sac, which is undoubtedly the shed " epithelial " coat of the 

 gizzard of the Darter. Where the " epithelium " t is thickest and best 

 developed, at the bottom of the gizzard, the walls have remained intact ; 

 but above, where it thins off towards the pyloric and ossophageal openings, 

 they have become broken, so that the sac is widely open here. A small 

 patch of the characteristic hairs (cf. Garrod, P. Z. S. 1876, p. 343, 

 pi. xxviii. fig. 2) of the pyloric part of the gizzard has come away with 

 the epithelium ; these alone would suffice to indicate the bird whence it 

 was derived. The hard epithelium does not extend above the limits of 

 the gizzard : hence none of the mucous coverings of the pro ventricular 

 gland or oesophagus has been preserved in the ejected specimen. The 

 outer surface of the cast epithelium is smooth and velvety, and exactly 

 similar in appearance to epithelium that has been peeled off the muscular 

 walls of the gizzard artificially. 



A microscopical examination of a part of the cast epithelium shows 

 that it is quite identical in structure with that of the unshed epithelium 

 of the stomach. 



I may add that in the stomach of a lately dead example of the species 

 though not that of the individual which " moulted " its stomach, which 

 is still (February 1) alive and in good health there is some appearance 

 of a similar " moult " being about to take place, the epithelial layer being 

 easily detached from the subjacent ones, whilst beneath it there is 

 apparently a new, though still very thin, coat of epithelium in course of 

 formation. This appearance is confirmed by sections of the epithelium. 



* Proc. Zool. Soc. 1881, p. 248. Read Feb. 1, 1881. 



t I use this term in the same sense as many previous writers have done, as a 

 convenient term for the object in question, without committing myself to any opinion 

 as to its true nature. W. A. F. 



