112 HYATT, 



of the endocyst. There is (1) an inner, large celled 

 membrane (PL 11, fig. 1, J') ; (2) one of smaller cells 

 (PL 11, fig. 1, J") ; (3) one of muscular fibre (PL 11, 

 fior. 1, J'") ; and (4) an epithelial layer lined with mus- 

 cular fibre (PL 11, fig. 1, J"") . 



(1) The cells of the first membrane, like those of 

 the first membrane of the endocyst, are large and resemble 

 hexagonal prisms with rounded ends. They have not, 

 however, the power of contracting and expanding individu- 

 ally, as in the first membrane of the evaginable endocyst, 

 and the thickness of the membrane is greatly increased 

 only when the cells are forced out in folds by the contrac- 

 tion of the walls. In the oesophagus they are of a yellow- 

 ish color, owing, probably, to the elaboration within them 

 of buccal secretions. In the stomach, this membrane is 

 permanently plicated, and the cells upon these plications 

 probably, in the absence of any specialized hepatic organ, 

 subserve the functions of a liver. They contain a brown 

 fluid described by Allman as an hepatic secretion, which is 

 liberated when needed by the rupture of the walls of the 

 cells. 



The membrane between these folds being of clear yel- 

 low color, the stomach appears externally, as if striped 

 with alternate longitud inal bands , of yellow and brown . It 

 is of a light brown color in the intestine of all the genera, 

 with the exception of Cristatella where it has a bluish tint. 



(2) The second layer is made up of small cells, 

 and retains about the same denee character throughout its 

 whole extent. A definite line of demarcation was found 

 above the funiculus, and this layer probably, does not cu- 

 ter iu the composition of that organ which appears to be 

 composed solely of the third and fourth layers. 



(3) In the third layer the fibres or muscular 

 cells are arranged transversely. A lateral view in section 

 shows them, like flattened cubes, resting upon the second 

 membrane. These transverse cells or fibres, compress the 

 walls, producing the peristaltic movements of the oesopha- 

 gus, stomach and intestine. 



[To be continued. The plates referred to were issued in vol. iv.] 



