32 ART. S. 1. IKEDA : THREE NEW AND 



section of the alimentary tract as in all following sections, the 

 longitudinal muscle layer (/.???.) lies internally to the circular 

 {cm.), the reverse of the order seen in the pharynx and the 

 œsophagus. The former layer is in contact with the basal surface 

 of the internal epithelium and is longitudinally folded. Where 

 the folds recede from the unfolded circular muscle layer there 

 exists a connective-tissue space of a considerable width. The 

 peritoneal covering (j^r.) of the crop is quite peculiar in that 

 here, as nowhere else on the entire alimentary canal, it is com- 

 posed of tall cylindrical or even club-shaped cells with coarsely 

 granular contents. 



In connection with the crop I may here deal with the 

 structure of the ventral mesentery which joins it to the ventral 

 body-wall. That mesentery (fig. 37, v.m., and fig. 39) is of a 

 considerable thickness ; it incloses in the interlamellar connective- 

 tissue layer sinus-like spaces in which are found some wandering 

 cells (fig. 39, w.c). These cells are quite indefinite in shape, 

 being sometimes elongate, sometimes ovoid and at other times 

 amœba-like. Most of them, but not all, contain in the cytoplasm 

 a limited number of yellowish brown spherules, which are in all 

 probability the same as those found in cœlomic corpuscles and 

 in the peritoneal cells to be directly described. As before men- 

 tioned, the ventral mesentery presents a glandular appearance in 

 the parts adjoining the crop (fig. 37, ffl.s.). This is due- to the 

 facts that the surfaces of the mesentery are thrown into numerous 

 small folds and that the peritoneal covering is thickened and is 

 converted into a peculiar structure. Fig. 39 shows highly mag- 

 nified a small portion of a cross-section through the mesenterial 

 part in question, with two folds on its side. It will be seen 

 that the peritoneum of this region is characterized firstly by the 



