750 



SYSTEMATIC HISTORY OF THE INFUSOEIA. 



datum (Corda), Stauroceras Acus (Kg.). 

 G.B.,I.,F.,G.,Italy. 



C. elegans (I3reb,). — Frond veiy slen- 

 der (twenty-five to thirty times as long 

 as broad), narrow-lanceolate^ upper and 

 lower margins nearly equally convex, 

 each extremity tapering into a long, slen- 

 der, setaceous, colourless beak, about as 

 long as the body, ultimately cui'ved do-svn- 

 wards, ends acute 5 large granules, in a 

 single series j e. f. without strice. F. 



C. setacemn (Ehr.). — Frond very slen- 

 der, from about twenty to twenty-five 

 times as long as broad, narroiv-lanceo- 

 late; upper and lower margins nearly 

 equally and hut slightly convex ; each ex- 

 tremity tapering into a very long, slen- 

 der, setaceous, colourless beak, longer 

 than the body, idtimately curved down- 

 wards, ends obtuse ; e. f. colourless, strice 

 close, faint, central suture solitary. Spo- 

 rangium cruciform, similar to the last. L. 

 1-116"; B. 1-2^Q\" . = Stauroceras subu- 

 latuni (Kg-)? ^' intermedium (Kg.), C. 

 KutzingU (Breb.). G.B., 1., F., G., Italy, 

 U.S.A. 



C. irronum (Breb.). — Frond very slen- 

 der (thirty to thirty-five times as long 

 as broad), nearly straight; upper and 

 lower margin scarcely inflated, nearly 

 equally though very slightly convex ; very 

 gradually attenuated at each extremity 

 into a long, slender, setaceous, colomless 

 beak, ultimately somewhat curved down- 

 wards, ends slightly enlarged and rounded', 

 e. f. colomless, without strice. F. 



7 * Frond minute, tapering, curvature 

 very slight, neither injlated nor rostrate. 

 {Sporangia cruciform.) 

 C. Cormi (Ehr.). — Frond minute, fr-om 



five to eight times as long as broad, 

 slender, slightly cun'ed, attenuated, etuis 

 blunt; endochrome not reaching to the 

 extremities ; large granules, indistinct, in 

 a single series ; e. f. colouiless, without 

 striae. Sporangium in f. v. somewhat 

 cruciform or quadrate, with the angles 

 produced and roimded, in s. v. elliptic, 

 attached to the conjugating fronds. L. 

 1-140" ; B. 1-3709". = C. tenue (Kg.). 

 G.B., F., I , G., Italy. ^, frond more tm*- 

 gid. L. 1-226" ; B. 1-2142". G.B., L, F. 



0. acutuni (Breb.), — Frond somewhat 

 larger than the last, about from six to 

 twenty times as long as broad, slender, 

 narrow-lanceolate, slightly curved, gi"a- 

 dually attenuated, ends acute ; e. f. co- 

 lourless, Avithout strise. Sporangium 

 similar to last. L. 1-177" ; B. 1-2550". 

 G.B., L, F., G. a six to twelve times 

 as long as broad, ends subacute. j3 ten 

 to twenty times as long as broad, ends 

 very acute. = Stauroceras subulatum 

 (Kg.)?, C. subulatmn (Breb.) ?, C. tener- 

 rim,um, (Kg.) ? 



C. Gripthii (Berk.). — Frond minute, 

 scarcely curved, acicular, verv acute, 

 smooth. = a subtile (Breb.) ? G.B., I., F. 



8 * Frond crescent-shaped, stout, extre- 

 mities furnished with a single acute 

 spine. 



C. euspidatum (Bailey). — Frond stout, 

 crescent-shaped, scarcely tapering, much 

 curved, ends rounded, furnished tvith a 

 single subulate acute sjnne ; e. f. without 

 striae. U.S.A. We are disposed to think 

 this plant may not be a true Desmidiean, 

 but belong to the genus Ophiocytium 

 (Nag.), though placed in Closterium by 

 Bailev. 



Genus PENIUM (Breb.). — Frond elongate, straight, cylindrical, elliptic, 

 or lanceolate, either not at all constricted or hut very slightly narrowed at the 

 middle, entire. Endochrome with or without a terminal clear space, con- 

 taining active granules. 



* Empty frond granidate, generally 

 reddish. 



Penium margaritaceum (Breb.). — 

 Frond six to ten times as long as broad, 

 fusiform or cylindrical, with rotundato- 

 truncate ends,\'ough with pearly gi-anules 

 arranged in longitudinal lines. Endo- 

 chrome at each end, sometimes with a 

 more or less distinct terminal cavity with 

 active granules. Sporangium orbicular, 

 smooth. = Closterium margaritaceum 

 (Ehr.). G.B.,L,F.,G. a, frond fusiform, 

 gradually constricted at the middle. 



granules distinct. L. 1-156" ; B. 1-961". 

 (11. 14.) /3, frond linear, scarcely con- 

 tracted at the middle, gTanides distinct, 

 y, frond linear, not contracted at the 

 middle, gTanules appearing like pimcta. 

 L. 1-169" ; B. 1-1515". (11. 15.) 



P. Cylindrus (Breb.).— Frond minute, 

 red, three or four- times as long as 

 broad, cylindrical, not contracted at the 

 middle, ends rotundato-truncate, rough 

 with minute, closely scattered, pearly 

 granules ; e. f. red. L. 1-492" ; B. 1760". 

 = Closterium Cylindrus(E\\v.),Dysphinc- 

 tium Cylindrus (Nag.). G.B., I., F., G. 



