448 



Eepprt op the State Geologist. 



tents ; the inner layer thus^eing the representative of the liver. 

 The median layer is composed of hexagonal cells, with a brilliant 



Fig. 18. a, Portion of Internal or hepatic layer of the stomach; h, Three isolated cells, further 

 magnified; each cell contains within it a secondary cell with brownish contents; c, Middle 

 layer of stomach composed of cells with colorless contents and brilliant nucleus; d, Structure of 

 the endocyst ; the tissue has been treated with acetic acid, and presents isolated nuclei, and nucle- 

 ated cells m various stages of formation; e, Muscular net work of the endocyst ; /, Muscular fibers 

 from the endocyst. treated with acetic acid and more highly magnified ; g. An Isolated muscle cell of 

 the same, still more highly magnified ; h, Tubular net work occasionally seen in the substance of the 

 endocyst, and containing peculiar corpuscles ; i, Corpuscles separated from the tubular net work • 

 1c, The same under the action of acetic acid. 



nucleus (fig. 18, c). The outer layer consists of a very thin mem- 

 brane with a cellular structure. It covers the whole of the 

 alimentary canal, and by the application of acetic acid it may be/ 

 frequently separated from the median layer. Delicate circular 

 striae may .be observed in this layer, in some species very dis- 

 tinctly. They are, in all probability, muscles. These muscles 

 have not been observed in this layer of. the intestine, but proba- 

 bly do occur there. In the oesophagus there are only two layers 

 (fig. 19, c, g\ corresponding to the median and external layer of 

 the stomach, the inner layer of the stomach having entirely dis- 

 appeared and the external layer being much thickened. The 

 mouth and upper portion of the oesophagus are thickly covered 

 with vibratile cilia ; apparently disappearing in the lower portion. 

 The structure of the intestine is very similar to that of the 

 oesophagus, with the exception that the cilia are entirely wanting. 



