OF THE DESMIDIE^. 



751 



P. annulatum (Nag. sp.). — Frond mi- 

 nute, scarcely tioice as long as broad, 

 cylindrical or suhelliptic, sides and ends 

 broadly rounded, rough ^dth minute gra- 

 nules arranged in transverse lines, whicli 

 give a minutely denticulate appearance 

 to the margin, except at a very nan'ow 

 central annular space, where they are 

 absent, thus imparting a somewhat con- 

 stricted appearance ; e. v. circular, margin 

 minutely granulate. = Dysphinctium an- 

 nulcdum (Nag.). I., G. 



2* Empty frond smooth, colourless. 



P. Digitus (Breb.). — Frond large, stout, 

 smooth, three or four times as long as 

 broad, elliptic - oblong, sides and ends 

 broadly rounded ; endochrome in obscure 

 and undulated fillets, interrupted only by 

 the pale central transverse band, and hay- 

 ing no clear space at the extremities. 

 L. 1-81"; B. 1-299". = Closterium Digitus 

 (Ehr.), Peniuni oblonqum (De Bary)? 

 G.B., I., R, G., U.S.A. 



P. lameUosum (Breb.). — Frond large, 

 stout, smooth, about four times as long 

 as broad, gradually contracted at the 

 middle, and tapering to the extremities, 

 ends somewhat truncate ; endochrome in 

 obscure and undulated filets, in transverse 

 view radiate, its rays divided, and hav- 

 ing no clear space at the extremities. 

 F., G. 



P. Ncegelii (Breb. in litt.). — Frond 

 large, stout, smooth, about four times 

 longer than broad, oblong, oiot contracted 

 at the middle, gradually tapering to each 

 exti'emity, sides nearly straight, ends 

 broadly truncate; endochrome arranged 

 in intej'rupted divided planes radiating 

 frojn the central axis, in f. v. being in' 

 dented somewhat in a pinnatijid manner, 

 the rays touchmg the cell wall, some- 



times divided, and somewhat dilated 

 thereat, in transverse view radiate. = 

 Closterium (Netriimi) Digitus (Niig.). 

 I., G. 



P. interruptum (Breb.). — Frond large, 

 stout, smooth, three or four times as long 

 as broad, cylindrical, sides parallel, ex- 

 tremities conical, and rounded at the ends ; 

 endochrome disposed in straight, strongly 

 marTxcd filets, interrupted by three trans- 

 verse pale bands, having a roimded, well- 

 defined clear space near the ends, in 

 which are active gi-anules. L. 1-116" ; 

 B. 1-571". (III. 45.) G.B., I., F., G., 

 U.S.A. 



P. closterioides (Ealfs). — Frond rather 

 large, about six times as long as broad, 

 smooth, fusiform or lanceolate, ends 

 broadly rounded ; endochrome in distinct 

 longitudinal fillets, interrupted only by 

 the central transverse pale band, with a 

 single longitudinal series of large granules, 

 and a rounded clear space close to the 

 ends, in which are active granules, L. 

 1-92"; B. 1-590". G.B., I., F., U.S.A. 



P. Navicula (Breb.). — Frond minute, 

 about three or fom' times as long as 

 broad, smooth, fusiform, ends bluntly 

 pointed; endochrome sometimes in fil- 

 lets, sometimes scattered, internipted 

 only by the transverse central pale band, 

 ivith one or two large gramdes in each 

 half, and a rounded clear space at the 

 ends, in which are active gi-anules. L. 

 1-420"; B. l-750".=V.£erginii(ArcheT). 

 I.,F. 



P. trunccdimi (Breb.). — Frond minute, 

 two to four times as long as broad, 

 cylindrical, smooth, ends trunccde. Spo- 

 rangimn orbicular, smooth, placed be- 

 tween the dehiscing, deciduous empty 

 fronds. L. 1-969" to 1-555" J B. 1-2212" 

 'to 1-2100". G.B.,I.,F. 



Genius SPIEOTJENIA (Breb.). — Frond elongate, straight, cylindrical, or 

 fusiform, entire, not constricted at the middle, ends rounded or acute ; endo- 

 chrome spiral. (Gelatinous investment very apparent ; ceU-division oblique ; 

 fructification unkno^Ti, therefore the position of this genus uncertain.) 



* Endochrome a single spiral ba^id. 



SpEROT^isnA condensata (Breb,). — 

 Frond cylindrical, five to ten times 

 as long as broad, ends rounded ; en- 

 dochrome a single, broad, closely-ivound 

 spiral band, its revolutiojis nimier'ous. L. 

 1-208" ; B. 1-1048". (n. 4.) G,B,, I,, 

 F,, G,,U,S,A, 



S, muscicola (De Bary), — Frond cylin- 

 drical, two to four times as long as 

 broad, ends rounded ; endochrome a 



single, broad, smoothly-defined, icidely- 

 ivound spiral band, its revolutions very 

 few (one or two). L, 1-142"' to 1-71'" ; 

 B, 1-2S7 "'.=Palmogl(ra endospira (Kg.), 

 Cylindrocystis endospira et Eridospira 

 trimcorum (Breb., Kg,), F,, G. 



S. erythrocephala (Itzigsohn, Braun). 

 Frond fusiform, five or six times as long 

 as broad,' ends acute ; endochrome a 

 single, rather narrow spiral band, its 

 revolutions few. = S. mimita (Thuret, 

 Breb.), F., G. 



