52 



THE AMERICAN MONTHLY 



[March, 



they do not adhere much to each 

 other ; the central orifice is small, 

 round or oval, with smooth edges. 



Longitudinally, fibres, fine, regular, 

 smooth, straight and stifi', easily sep- 

 arated from each other in the bundles ; 

 thickness of the partitions very uni- 

 form ; central canal small but very 

 distinct ; points elongated and sharp. 



L. 9"'™ ; D. o""'. oi6 ; 



R. 560 Phormium. 



b. Polygonal sections with very ob- 

 tuse angles or oval shapes ; very close 

 contact between the groups ; parti- 

 tions generally of moderate thickness ; 

 central orifice large, resembling in its 

 form that of the outer perimeter, but 

 the angles are so small that the open- 

 ing appears nearly round or oval ; it 

 sometimes contains brown granula- 

 tions. 



Longitudinally, fibres, smooth, reg- 

 ular, of a very uniform but inconsid- 

 erable thickness ; central canal large 

 and plain ; points tapering regularly 

 and gradually, sharp or slightly round- 

 ed at the end. 



L. 6"'"' ; D. o""", 020 ; 



R. 250 Abaca. 



c. Sections of a yellowish brown 

 color, round or oval, scarcely touch- 

 ing in the groups, enclosed in a net- 

 work of thick meshes, which unites 

 them into very compact groups, having 

 in their center an empty space or gap 

 of irregular form ; the central oi'ifice 

 of the fibre very large, round or oval. 



Longitudinally, fibres, very short, 

 stifi*, with quite thick partitions, not 

 equalling, however, the size of the 

 interior canal ; the exterior contours 

 often sinuous or toothed ; walls some- 

 times interrupted by solution of con- 

 tinuity (pores ?) ; points rounded or 

 abruptly terminating ; brown bundles 

 very compact and easily separated. 



L. 0°"", 7 ; D. o"'"', 020 : 



R. 35 . . Coco. 



2. Sections polygonal, clearly de- 

 fined ; central orifice equally polyg- 

 onal, with angles more or less dimin- 

 ished, and traces of fibro-vascular 

 bundles. 



a. Polygonal sections, often with 

 obtuse angles, partitions not very 

 thick ; central orifice polygonal, with 

 smooth and angular perimeter, always 

 empty. Longitudinall}', bundles, 

 very compact, almost indivisible, 

 composed of fine fibres, smooth, stifi', 

 with thin partitions, of uniform thick- 

 ness ; central canal large ; points 

 shai'p, slender. 



L. 3""" ; D. o""", 030 ; 



R. 150 Sanseviera. 



b. Polygonal sections, with straight 

 sides and angles sometimes a little 

 blunted ; central opening very large, 

 polygonal, with angles less pro- 

 nounced than the outer ones ; fis- 

 sures in the walls, perpendicular to 

 the exterior and interior contours. 



Longitudinally, fibres, short, stiff', 

 with thin walls swelled toward the 

 centre ; thickness of the walls very 

 imequal ; the outer profile often wavy 

 or toothed down to the large point 

 shaped like the scabbard of a sabre 

 and sometimes bifurcated. 



L. 3'""', 5 ; D. o""", 035 ; 



R. 100 Pita. 



Vorticellte with two Contractile 

 Vesicles. 



BY DR. A. C. STOKES. 



Recently I sent to the American 

 Naturalist a communication to the 

 effect that not only does Vorticella 

 Lockxvoodii Stokes possess two pul- 

 satmg vacuoles, but that the same 

 number is apparent in [ orticella 

 nionilata Tatem, and I expressed sur- 

 prise that this fact should have been 

 for so long overlooked, since the last- 

 named form is not uncommon in 

 Europe nor rare in our own waters. 

 My wonderment at such an oversight 

 is not now so great as it was, for 

 hardly had the manuscript to the 

 Naturalist passed out of my hands 

 when I captured two individuals of 

 Vorticella vcstita Stokes, which had 

 not been previously obtained since 

 its description in this Journal of 

 Noveml)er, 1883, and I found that 



