CALOCYLINDRUS. 27 



somewhat attenuated ; apices roundly truncate ; membrane 

 hyaline, punctate, thickest at the ends 110 aculei nor teeth. 



Diameter of cells, basal parts 54 ^ ; middle 75 // ; 

 apices 39 jw. 



Pond waters, Georgia. 



D. VERTICILLATUM, ( Triploceros verticiUatum, Bail.) V. Des. IT. S. 



p. 53. Plate LXI, fig. 18. 



This illustration given as another of many forms in which 

 this species often occurs. The third diverging process of 

 the apical termination not always evident. 



W. N. Hastings, Rochester, New Hampshire, reports this 

 form frequent in the Cocheco River. 



Genus, CALOCYLINDRUS. V. Des. U. S. p. 54. 



C. DE BABYI, Arch. Plate LVI, fig. 12. 



A specimen from Minnesota, the typical form, unlike the 

 one fig. 5, Plate XV, which is more like a form of C. Cu- 

 cumis f the constriction is not deep, linear, but merely a 

 shallow notch, hence De Bary classified it with Pleurotaenium. 



C. CORDANUM, Breb. Plate LX, fig. 28. 



Diameter about half the length ; gently and slightly con- 

 stricted in the middle ; ends round or somewhat trun- 

 cate ; cytioderm lightly granular or punctate. End view 

 circular. 



Diameter 26-27 ^ length 47-50 ^ ; isthmus 17-19 //. 



This form is reported by W. B. Turner, as found in Nova 

 Scotia. 



Genus, COSMARIUM. V. Des. U. S. p. 57. 



C. INFLATUM, Wolle. Plate LVII, figs. 18, 19. 



Cells one-half longer than broad j semi-cell gradually en- 

 larged from a narrow base to a broadly dilated end ; end 

 view broadly elliptic ; lateral view circular, with somewhat 

 flattened sides ; membrane finely punctate or smooth. 



Diameter 25-28 // ; length about 40 /*. 

 Ponds, Minnesota. 



(7. pseudoprotuberans, Kirch., has something in common 

 with this form, but the semi-cells are separated by narrow 

 linear sinuses. (7. inflatum has wide obtuse angled sinuses. 



