66S 



PROCEEDINGS OF THE ACADEMY OF 



[Sept., 



Analysis of Species. 



I. — Lorica nearly spherical. 



Surface smooth or nearly so, T. volrocina. 



Surface f Hemispherical elevations, T. verrucosa. 



marked \ Obliquely transverse, irregular, crooked wrinkles, . . T. rugulosn. 

 with [ Longitudinal, somewhat oblique, continuous ridges, . T. Stokesiana. 



Surface 

 nearly 

 smooth. 



II. — Lorica not spherical. 



f Not caudate, aperture produced, (, Narrowly cylindrical, T.cylindrica. 

 I outline somewhat quadrate, \ Broader, flask-shaped, T. euchlora. 



f Vasiform, aperture denticulate, 

 j Caudate, aperture produced, | T. urceolata. 



outline not quadrate. 



General 



surface 



not 

 smooth. 



j Pyriform, aperture smooth, oblique, 

 [ T. acuminata. 



\ Not caudate, outline ovate, aperture rim wide, crenulate, 

 L T. eury stoma. 



Spirally ridged. Aperture in an oblique groove, . . . T. torta. 

 \ PunctiB fine, uniform, f A posterior cro«Ti of large spines 



=---'-'» ar:C,STiu.?r^ 1 No p„.,.er,„r spin^, ' ^"''' " 



^ L * i . acanthostoma. 



[ Punctae coarse, irregular, T. crebea. 



Reticulate. Lorica ovoid. Cell-contents colorless, . T. reticulata. 



( Ovoid, ends equally rounded, 

 Spines short, stout, ! T. hispida. 



thickly set. ) Tapering posteriorly, caudate, 



[ T. caudata. 



{ Rounded in front, obtusely conical poste- 



Spiny. \ Spines short, I riorly, T. obtusa. 



more slender, J f Neck conically contracted, 



less thickly j Both ends 1 T. bulla. 



set. rounded. | Neck trumpet-form, spiny, 



[ (. T. piscatoris. 



Spines long and large, numerous. Neck trumpet-form, 



[ wa\'y, T. horrida 



Trachelomonas volvocina Ehr. 



Trachelomonas volvocina Ehrenberg. 1833. Abh. Berlin. Akad. 



Lorica spheroidal, brown, surface nearly smooth. Aperture plane 

 or produced into a cylindrical tube, which may be normal to the surface 

 or slightly oblique. 



This is perhaps the most common of local species, and very variable. 

 The lorica may be prolately — or oblately — spheroidal, and of any size 

 from very minute to 29 // in diameter. The oblately spheroidal forms 

 seldom exhibit any tube-like prolongation, but often a wide saucer- 

 shaped depression surrounds the aperture and the wall is at that point 

 very heavy. The tube, when present, may be altogether without the 

 lorica, or partly within it and attached to the apex of a funnel-shaped 

 depression in the wall. The surface of the finished lorica is almost 

 smooth, or at most slightly wavy, though the intimate granular nature 

 of the wall may at times be made out. 



