THE AMERICAN NATURALIST 



[Vol. LV 



which sac is 73, 82, 100, 112, when tube is 27, 27, 50, 37. 

 Width 90-120, narrowest width 40-70. Diameter of 

 swelling of tube 50-80, width of tube about 30-50. Diam- 

 eter of nucleus from 15-32. 



The Chesapeake forms have a much flattened sac, some 

 130-140 long by 195-110 wide, but only 30 deep. The 

 exact point of passing to tube is various; the tube may 

 be regarded as 25-55 wide and swelling to 57 wide, though 

 it may be but 25 at actual mouth, which rarely has a col- 

 lar, but may have a flaring of 6 fi. The length of tube 

 may be 30, making the length over all 175. The tube may 

 turn upw^ard from attachment nearly 50 when sac is but 

 30 deep. The nucleus is from 15 by 17 to 15 by 27. 



The halo of secretion about sac is some 7 ft or more in 

 thickness. Characteristic of some specimens is the valve, 

 so-called, relied upon by Dons as of generic value. This 

 appears as a dorsal and ventral flap of membrane within 

 the sac at its continuation as the tube and projects for- 

 ward. These two membranes converge to meet below 

 the center of the cavity, which they close off more or less 

 completely. They vary in number and position and often 

 seem to be lacking. 



A description of these amphora forms of the Chesa- 

 peake will be published elsewhere and we will here merely 

 add a summary of the foregoing consideration of the 

 probable position of the known American folliculinas in 

 the tentative scheme of classification of the family. 



Following Dons we may separate the Folliculinas from 

 the Stentors on account of the more or less marked de- 

 velopment of the body as lateral lobes which make a 

 funnel leading toward the mouth and which may be re- 

 garded as a specialization of the more primitive feeding 

 apparatus found in Stentor. 



The Folliculinidfe are thus Heterotrichia with spindle- 

 shaped body prolonged as lateral lobes to form a funnel 

 leading toward the mouth and marked ability to secrete 

 dwellings composed of a sac-like part more or less pro- 

 longed as a tube which may reach great length and ex- 

 hibit spiral structure. 



