1919] Kofaid-Swczy: Lcidyopsis sphaerica 103 



Surface RrocES : The outer layer of ectoplasm is raised in narrow 

 longitudinal ridges (fig. A, swr/. rdg.) from the crests of whicli spring 

 the flagella. The ridges extend from the base of the operculum at 

 the anterior end posteriorly for about one-third to one-half the length 

 of the body. Anteriorly they are very narrow and placed close 

 together, the ends forming an irregular, wavy line around the base 

 of the operculum (pi. 13, fig. 10). Posteriorly they spread out in 

 fan-shaped or radiating lines, increasing in number by the inter- 

 positiozi of new ridges. Their course is longitudinal withoiit spiral 

 twisting, and when the limits of the differentiated ectoplasm are 

 reached they disappear in the thin periplast of that region. 



Locomotor Orgajmelles : These are confined to the anterior third 

 of the body, and consist of long flagella, approximately equal in length 

 and arising in longitudinal rows from the crests of the surface ridges. 

 They are most numerous anteriorly on the cone-shaped portion of the 

 body, where they form a dense mass which retains the dark color of 

 iron haematoxylin. A single flagellum alone does not show the stain 

 nor do the ends which stream out from this mass. Collectively, how- 

 ever, thej^ are usually stained so darkly as to obscure the nucleus and 

 other structures beneath them. The spreading apart of the surface 

 ridges distally results in a distinct thinning of the coating of flagella 

 behind the narrowed anterior end of the body. 



Each flagellum arises from a minute basal granule below the 

 surface ridges, passes up through the ridge and leaves the crests as 

 a single thread. Each basal granule is connected with a minute fibril 

 from the oblique fibers, apparently in the same manner as in Trioo- 

 nympha (ximpanula. These fibrils and basal portions of the flagella 

 give a finely striate appearance to the layers of ectoplasm through 

 which they pass. 



The flagella stream outward and backward over the surface of the 

 body and in the living flagellate are in constant motion. 



Oblique Fibers: These are not so prominent in Leidyopsis as 

 in Trichoinjmpha, owing partly to their smaller extent, and partly 

 to tlie difficulty of differentiating them from the mass of dark flagella. 

 Wlien the flagella have been sufficiently destained to allow observa- 

 tion of the structures beneath them, the latter have also completely 

 lost their color, and only the most careful focusing enables the observer 

 to distinguish between the flagella and the equally slender oblique 

 fibers immediately beneath. 



The oblique fibers form an integral part of the centroblepharoplast 



