434 SUMMARY OF CURRENT RESEARCHES RELATING TO 



drical epithelium and a cuticle, the surface of which presents spiny 

 prolongations. On the upper surface there are papillae, and on the 

 lower portion of the outer face the cuticle disappears, and there are 

 seen large papillfe covered by an epithelium and large glandular cells. 

 The submandibular gland, which the author believes he is the first to 

 describe, is situated immediately behind the lower jaw ; it is oval in 

 form and its long axis runs antero-posteriorly ; racemose in appear- 

 ance, the acini are separated by connective tissue arranged in delicate 

 layers ; some of the acini contain polyhedral cells, the protoplasm in 

 which is granular ; others have the epithelium cylindrical, and these 

 appear to be sections of the collecting ducts. The author has no 

 opinion as to the function of this organ. The salivary glands are 

 well developed, and consist of two pairs ; in structure they are very 

 similar to the salivary glands of the higher Vertebrata, and the author 

 even compares the duct to the Stenonian canal. 



The oesophagus presents numerous longitudinal folds of the mucous 

 membrane, and the same structure is found from the mouth as far as 

 the gizzard or true stomach. Perpendicular sections of the wall 

 reveal the presence of, from within outwards, a cuticular layer 

 coloured yellow by picrocarmine, a layer of cylindrical epithelial 

 cells arranged in a single row, a mucous layer containing connective- 

 tissue and elastic fibres, and adapted to admit of the extension of the 

 walls of this region. The succeeding muscle is arranged in two 

 layers, one circular and one longitudinal, and in the non-distended 

 condition this portion appears to be thicker in the region of the crop 

 than in that of the oesophagus ; then comes another layer of connec- 

 tive tissue, which supports a simple layer of pavement epithelium, 

 and these are regarded by the author as analogous to a peritoneum. 

 The gizzard has very thick walls, its inner surface is deeply grooved, 

 and a hard plate is to be found in the centre of the anterior and 

 posterior faces. The thick lining cuticle may, as in birds, be removed 

 in a single piece ; it exhibits no solution of continuity, and there are 

 no glandular orifices to be detected in it ; the striated appearance is 

 due only to its mode of formation, as it is absolutely structureless. 

 The glands were found in the subjacent epithelium, and the exact 

 function of the organ is made apparent by their absence. The 

 muscular layer, some of the fibres of which take a vertical direction, 

 makes up the chief part of the walls. Vibratile cilia were detected 

 on the cells of the intestine ; these cells are either cylindro-conical 

 or calyciform (these become rarer as the rectal region is reached), 

 and the latter are the sole glandular elements which are found in the 

 walls of the intestine. 



In the neighbourhood of the gizzard there is a spiral caecum, the 

 internal surface of which presents the appearance of valvulse conni- 

 ventes ; these are composite, their two faces being invested by smaller 

 valvular folds; the cylindro-conical epithelial cells are ciliated, and 

 in addition to them there are polyhedral cells which appear to belong 

 to special glands, to which the author proposes to give the name of 

 rahular glands. 



The liver is very voluminous, and is not lobed ; it is very soft ; 



