OF THE PEDIASTPvE^. 



755 



P. Boryamim (Menegli.). — Cells ar- 

 ranged in one or more circles round one 

 or two central ; the inner variable, gene- 

 rally concave at one side, the outer taper- 

 ing into two long subulate jioints, the notch 

 narrow. L. 1-2083" to 1-1633"; B. 

 1-2733" to 1-2222". (i. 59, 60, 61, 68, 

 69, microgonidia.) = Blicrasterias JBory- 

 ana (Elir.), P. suhuUferum (Kg.), P. cru- 

 ciatum (Kg.). G.B'., L, F., G., U.S.A. 



P. ellipticum (Hass.). — Cells A'arying 

 in number and arrangement ; outer cells 

 suddenly contracted into two short, cylin- 

 drical, obtuse processes. L. 1-1754" to 

 1-906" ; B. 1-1515" to 1-1020". /3, pro- 

 cesses of the lobes truncato-emarginjite. 

 = 3Iic)'osterias elliptica (Ehr.), P. vagum 

 (Kg.), P. constrict um (Hass., Kg.)? P- ^^- 

 dentulatum (Braun). G.B., I., G., U.S.A. 



P. angulosuni (Menegh.). — Cells ar- 

 ranged in one or more circles round one 

 central, the inner cells roundly angular, 

 the outer obliquely truncate, emarginate, 

 the subdivisions not tapering into rays. 

 L. 1-2732" ; B. 1-1942". = Micrasterias 

 angulosa (Ehr.). G.B., R, G. 



3 * Outer cells with only one attenuated 

 lobe (Monactinus). 



P. simplex (Meyen). — Cells eight, in a 

 single series surrounding a central vacant 

 interval, narrow-ovate or lanceolate, very 

 gi'adually tapering, acimiinate, approxi- 

 mate only at their hases. = 3Ionactinus 

 mnplej: (Kg.), M. simplex et acutangulus ' (i. 46, 47, 48). G. 



(Corda), 3/. octonarius (Bail.) ? F., G., 



U.S.A. There seems to us to be some 



doubt as to the absolute distinctness of 



this and P. gracile (Braun), as it is pos- 



j sible the four deeply bipartite external 



I cells of the latter may have been mis- 



j taken for eight simply attenuated cells 



i as described for P. simplex (Meyen). 



j P. duodenarium (Bailey, sp.). — Inner 



I cells/o«/-, somewhat triangular, enclosing 



I a central, quadrate vacant interval, and 



j four broadly lanceolate vacant intervals 



I between them and the outer series, to 



t which they are united by their terminal 



angles ; outer cells twelve, subovate, 



: truncate below, much attenuated, acu- 



; minate. = Monactinus duodenarius ( Bail. ) . 



I U.S.A. 



! P. ovatum (Braun). — Cells ovate, ter- 

 1 minating in a long, acute point, granu- 

 late, arranged in tv\^o series, inner three, 

 I outer ten.=Asterodictyon ovatum (Ehr.), 

 i Monactinus ovatus (Kg.). G. 

 : P. Triangulum (Braun). — Cells trian- 

 gular, smooth, arranged in three series, 

 the centre vacant. Asterodictyon Trian- 

 gulum (Ehr.) = 3Io)iactinus I'riangulum 

 (Kg.). G. 



4* Oute?' cells not lobed (Anomopedium). 



P. integrum (Niig.). — Frond irregidar, 

 cells rounded or bluntly angular ; outer 

 cells not emarginate, generally possessing 

 externally two short mucro-like spines 



Genus CCELASTBUM (Niig.). — Frond or family hollow, globular or sub- 

 cubical, composed of polygonal (or spherical) cells united in one layer into a 

 hollow clathrate net-lihe family, the cells drawn out on the exterior into one 

 or more lobes, or simply spherical ; propagating by the segmentation of the 

 cell-contents into a definite number of portions which become arranged into 

 a hollow young frond resembling the parent, ultimately set free by the 

 bursting of the parent- cell. 



Ccelasthum sph^ricum (Nag.). — 

 Fronds spherical or oval ; cells hex- 

 agonal, dra^^Ti out externally into a 

 blunt cone, interstices 5-6-angular. (i. 

 49,50,51.) G. 



Ccubicum (Nag.). — Frond subcubical. 



cells hexagonal, drawn out externally 

 into two short truncate projections, in- 

 terstices quadrangular, (i. 54, 55. ) G. 



C. microporus (Nag.). — Frond globu- 

 lar, ceUs exactly spherical, interstices 

 minute. G. 



Genus SORASTRUM (Kg.). — Frond or family solid, globular, composed of 

 cuneiform or cordate cells, somewhat compressed and united into globular 

 families, their narrow ends meeting in the centre and outwardly emarginate 

 or divided. Propagation unknown. 



SoRASTRUM sjnnidosum (Nag.). — Ex- 

 ternal margins of the cells dilated, 

 slightly emarginate, the rounded angles 

 furnished each with two minute, acute. 



subulate spines, (i. 56, 57, 58.) G. 

 S. echinatum (Kg.). — External mar- 



gins of the cells deeply 

 divisions subulate. G. 



bifid, the sub- 

 3c2 



