No. 3-] MORPHOLOGY OF THE STENTORS. 475 



morphus, and I have been unable to keep them more than a 

 month. Although I have examined a large number, I have 

 never found one in fission. 



In April, 1892, I visited another colony of S. pyriformis in 

 Lake Quinsigamond, for information in regard to which I am 

 indebted to my friend Dr. Wm. S. Miller. This colony is 

 located in a winding, shallow bay known as "the Sanctuary." 

 About two acres of the bottom are literally covered with these 

 Stentors, which give it the appearance of being overgrown 

 with a minute green vegetation. The Stentors live at various 

 depths down to four or five feet. The earliest specimens 

 collected (April 1 8) contained much less chlorophyll than those 

 obtained in the fall, and in many the very narrow and obscure 

 stripes were visible, which is never the case when the zoochlo- 

 rellae are abundant. The specimens, furthermore, were inert, 

 remained constantly contracted, and in many cases I could not 

 distinguish the adoral zone. I believe, therefore, that they 

 had recently emerged from the cyst. Stentors collected at 

 the same place April 23 were more active, and contained a 

 much greater quantity of zoochlorellae. 



Characters : Large {length, extended, .5 mm., breadth across 

 frontal field, .2 mm.) / in extension, funnel-shaped, elongate 

 conical, or pyriform ; in semi-contraction, pyriforni or nearly 

 cylindrical ; anterior tJiird of body of nearly nniform diameter, 

 same as frontal field ; posterior extremity obtuse, rounded ; 

 stripes very obscure, narrow {3.5/* ^i^ width) generally not 

 visible in living animal ; adoral zone narrow, fnevibranellce 

 iveak, oral aperture placed considerably posterior to aboral 

 extremity of zone ; endoplasm zvhitish, opaque, crozvded out- 

 wardly with zodchlorell(E ; no pigment ; contractile vesicle in 

 usual position, to left of mouth (Fig. 2, c.v.) ; a single mega- 

 nucleus rarely observed, nearly always 2-4, spherical or oval, 

 40fi in dia^neter. Hab., Lake Quinsigamond, Worcester, Mass. 



S. pyriformis obviously belongs to the group of small Sten- 

 tors with simple, spherical meganuclei, and lowly-organized 

 frontal field. Its nearest ally is evidently 5. igneus, from 

 which it differs in its much greater size, entire absence of 

 pigment, thicker form when extended, and narrower stripes. 



