THE INDIAN DARTER. 327 



has no such plug. In P. melanogaster the two gland-patches have the 

 form of watch-pockets, which nearly, though not quite, unite with each 

 other superiorly. They measure 1*1 inch transversely and *8 inch from 

 above downwards, being thus a little larger than the similarly shaped 

 and situated ones of P. levaillanti *. There is no trace of the elevated 

 " U-shaped ridge " situated on the anterior wall of the stomach between 

 the two patches, described and figured by Prof. Garrod in the last- 

 named species. The gland-patches are covered, as is the rest of the 

 interior of the stomach, by the usual yellow wrinkled "epithelium." 

 This ceases abruptly above at the level of the upper margins of the 

 glandular areas, where it meets the smooth and pink mucous membrane 

 of the oesophagus. Along this line of junction, the epithelial coat is 

 thicker and jagged, an appearance probably due to several thicknesses of 

 this coat having been " moulted " (as we know happens in the American 

 species) and not come clean away t. 



The second, or pyloric, stomach is quite as distinct in Plotus mela- 

 nogaster as it is in the two other species of the genus dissected. Like 

 these, too, its pyloric half is covered internally with the peculiar hairy 

 mat already described in these birds : the cardiac part, on the other 

 hand, is covered by a yellow " epithelium " continuous with that of the 

 rest of the stomach. The hairy covering forms a complete ring, thickest 

 and best developed inferiorly on the surface corresponding to the 

 "greater curvature "of the Mammalian stomach and quite surround- 

 ing the equally hairy pyloric plug. This " plug " is not a free process : 

 it is rather a well-defined ridge, nearly cylindrical in section, attached 

 superiorly to the wall of the stomach, but ending freely below. It, 

 particularly towards its termination, is thickly covered with hairs of a 

 similar character to those in the rest of the hairy region. When fully 

 retracted, it completely fills up the centre of the hairy ring already 

 described, the communication of the cavities of the stomach and duode- 

 num being reduced to a narrow aperture situated below the plug, and 

 only capable of allowing the passage of a bristle. 



It is not unusual in birds to find a small irregular .nipple-like pro- ** ^ & 1882, 

 jection guarding the entrance to the pylorus ; and it is, I am inclined to P> 

 believe, a greatly developed condition of this structure that forms the 

 hairy " plug" of the Old- World Darters. 



In the rest of its anatomy Plotus melanogaster resembles in nearly 

 every respect P. anhinga and P. levaillanti. As in the latter, there are 

 two caeca, '2 inch long, whilst in most specimens of P. anhinga one only 



* In the prYentricular glands being limited to distinct areas, which do not unite 

 to form a zone, Plotus levaillanti and P. melanogaster resemble the genus Phalacro- 

 corax. 



t Cf. Bartlett, P. Z. S. 1881, p. 247. 



