1919] Kofoid-Swczy: Lcidyopsis sphacrica 105 



Alveolar Layer : This is closely associated with the oblique fibers, 

 occupying the same I'egion of ectoplasm. It is difficult to demonstrate 

 and sometimes appears to be entirely lacking. This, however, seems 

 to be due to the small extent of the ectoplasmic layer which it 

 covers in those cases. In only a few specimens does it extend as far 

 postei'iorly as do the other ectoplasmic structures. It seems to be 

 the first part to disappear in the thinning of the ectoplasm, which 

 takes place a short distance behind the base of the cone. 



The alveoli are most prominent at the time of division and appear 

 in surface view as small, colorless spheres, varying considerably in 

 size, and not closely packed together (pi. 14, fig. 24). In the ordinary 

 trophozoite the arrangement is more compact, with the individual 

 alveoli of smaller size. 



Endoplasmic Structures 



The endoplasm may be divided into two regions, anterior and 

 posterior, but with no definite boundary line separating them. The 

 distinction between the two portions is rather less pronounced in this 

 form than in the different species of Trichonynipha. 



The anterior part is relatively small, extending but a short dis- 

 tance behind the nucleus (pi. 13, fig. 1). It is granular, without 

 alveoli or food inclusions. The part immediately surrounding the 

 nucleus is usually more dense than the remaining portion, evidently 

 the result of greater metabolic activity. 



The posterior region of endoplasm is coarsely vacuolate in structure 

 and is often abundantly filled with food bodies (fig. A, /. &.). These 

 are sometimes found enclosed in food vacuoles but more frequently 

 are found lying free in the plasma. They consist of particles of 

 wood, small flagellates, bacteria, or other small bodies that may be 

 present in the intestinal contents. The method of ingestion of these 

 is entirely unknown. No cytostome is present unless it is possible for 

 the cup-shaped depression at the anterior tip of the body to assume 

 that function. Neither the feeding reactions nor defecation of Leidy- 

 opsk have been observed. 



Longitudinal Myonemes: These mj'onemes are found in the 

 outer zone of endoplasm, immediately beneath the ectoplasm of the 

 anterior part of the body, and coextensive with it. They are granular 

 in structure and form straight, longitudinal lines radiating out from 

 the region of the centroblepharoplast (fig. A, long. my.). Their 

 connection with that structure, if any exists, could not be clearly 

 detected. 



