1885.] 



MICROSCOPICAL JOURNAL. 



71 



of a hard, crustaceous, greenish 

 thallus. Oocardium^ 30. 



Genera of doubtful value, omitted 

 in this classification : — 

 Ta ch ygo n in in Niige H . 

 Palniophylluin Kiitzing. 



a. Separate. 



1 . Genus Ercmosphccra De Bary. 

 Cells spherical, free - swimming ; 



walls thick, firm, hyaline ; contents 

 green, granulose, sometimes radiat- 

 ing in laminae or plates from the cen- 

 tre of the cell. 



Propagation by division into 2-4 

 daughter-cells, each of which escapes 

 by a special rupture in the cell-wall. 

 Zoogonidia not known. 



2. Genus PIeurococc7is Kirchner. 

 Cells spherical, or p o 1 y h e d r i c 



through mutual pressure, with thin, 

 not confluent walls, single or in small 

 spherical or cubical aggregations ; 

 contents green, red, or reddish-yel- 

 low. Division in every direction. 



Propagation by gonidia, not ob- 

 served in all species. 



3. Genus Dactylococcus Nageli. 

 Cells oblong or spindle-form, free 



swimming, with thin walls, forming 

 families of 2-8 cells by oblique di- 

 .vision, the cells finally separating 

 and becoming single. Contents 

 green, with one starch granule. 



[The cells of. Dactylococctis are 

 enclosed in ample hyaline sheaths, 

 which are stiptate, or attenuated into 

 a pedicel which is attached to some 

 object. D. De Baryanus^ for ex- 

 ample, is parasitic on small aquatic 

 crustaceans, such as entomostraca.] 



4. Genus Stichococcus Nageli. 

 Cells oblong, or short-cylindric 



through mutual lateral pressure, with 

 thin walls ; single or joined serially 

 into small, free-lying families ; con- 

 tents green ; division only in one di- 

 rection. 



5. Genus Raphidiutti Kiitzing. 



Cells fusiform, cylindric or needle- 

 shape, ends usually cuspidate or acu- 

 minate, straight or curved ; single, or 

 two joined end to end, or in fascicles 

 pr bundles ; walla thin ; contents 



green, with a central or rarely lat- 

 eral vacuole. Division perpendicu- 

 lar to the longer axis. 



b. Inclus.-e. 



6. Genus Botrydina Br^bisson. 

 Cells spherical or oblong, with 



thick, gelatinous, partially confluent 

 integument, associated in families, 

 sometimes very large, closely sur- 

 rounded by the expanded membrane 

 of the original mother-cell, which 

 constitutes a sub-globose thallus. 

 Contents green. 



7. Genus Botryococcus Kutzing. 

 Cells oval or elliptical, with thin 



walls, united in a small solid, botry- 

 oidal family (like a bunch of grapes) , 

 which is very closely enveloped by 

 the thin, difterent membrane of the 

 original mother-cell. Contents green, 

 reddish or brownish. 



8. Genus Gloeocystis Nageli. 



Cells globose, with gelatinous en- 

 velopes ; single or 2, 4-8 associated 

 in globose gelatinous families ; special 

 and general envelopes 1 a m e 1 1 o s e . 

 Contents green, with a starch-granule 

 and a vacuole, rarely red. Division 

 in alternate directions. 



Propagation by motile gonidia. 



[The peculiar lamellose structure 

 of the gelatinous matrix distinguishes 

 this plant from Pletwococcus. 



We are inclined to place the very 

 closely allied Glceocapsa in this fam- 

 ily, particularly since the observations 

 of Paul Richter* tend to prove that 

 Glceocapsa and Gloeocystis are the 

 same plant under difterent conditions 

 of growth. Both these genera are 

 found in moist situations, exposed to 

 the air, but never under wa^^er, since 

 in water their gelatinous investments 

 disappear. 



The beginner may be puzzled at 

 times to distinguish between the two 

 genera. In a general way it may be 

 said that the lamellose structure is 

 more distinct in Gloeocystis than 

 in Glceocapsa^ and the former is 

 usually green, while Ae latter is 

 olive or bluish-green. Some species 



• See this Journal, vol. ii, pp. 25 and 52. 



