CERAMIUM. 



[ 127 ] 



CERCOMONAS. 



3. antheridia, produced in the same situa- 

 tions as the spores. British genera : 



I. Ptilota. Frond compressed, inarticulate, 

 distichous, pectinate-pinnate. Favellte pe- 

 dunculate, involucrate. 



II. Microcladia. Frond filiform, inarti- 

 culate, dichotomous. Favellce sessile, invo- 

 lucrate. 



III. Ceramium. Frond filiform, articulate, 

 dichotomous ; the joints opake. Favellce 

 sessile, mostly involucrate. Tetraspores 

 mostly immersed. 



IV. Spyridia. Frond filiform, inarticu- 

 late ; the branches clothed with minute, 

 setiform, articulated ramelli. Favellce pe- 

 dunculate, involucrate. Tetraspores sessile 

 on the ramelli. 



V. Griffithsia. Frond articulated, dicho- 

 tomous, or clothed with whorled, dichotomous 

 ramelli, rose-red. Favellce involucrate, 

 sessile or pedunculate. Tetraspores sessile, 

 on whorled ramelli. 



VI. Wrangelia. Frond articulated, pin- 

 nate. Favellce terminal, involucrate, con- 

 taining tufts of pear-shaped spores. Tetra- 

 spores sessile, scattered on the ramelli. 



VII. Seirospora. Frond articulated. Te- 

 traspores arranged in terminal, moniliform 

 strings. 



VIII. Callithamnion. Frond, at least 

 the branches and ramuli, articulated, mostly 

 pinnated. Favellce terminal or lateral, sessile, 

 without involucre (except in C. Turneri). 

 Tetraspores sessile or pedicellate, scattered. 



IX. Trentepohlia. Frond articulated, 

 branched, cells in single series. Favellcs (?) 

 in terminal corymbs. 



BIBL. Harvey, Man. Brit. Marine Algce. 

 See also the Genera. 



CERAMIUM, Roth. A genus of Cera- 

 miaceae (Florideous Algae), containing a 

 number of species, mostly growing between 



Fig. 118. 



Ceramium Delongschampii. 



Fragment of a frond showing one tetraspore in situ, and 

 two empty parent-cells. Magnified 50 diameters. 



tide-marks, of which C. ciliatum is noted as 

 a beautiful object under a low magnifying 

 power. The][tetraspores are often only triple, 

 and arranged tetrahedrally and not in a row 

 (fig. 118). 



BIBL. Harvey, Brit. Mar. Algce, pi. 22 C.; 

 PJiyc. Britann. pi. 139-41, &c.'&c. 



CERATIDIUM, Ehr. A genus of Infu- 

 soria, of the family Oxytrichina. 



Char. Furnished with cilia, horns on the 

 fore-part of the body, but neither hooks nor 

 styles. 



One species, C. cuneatum. Dujardin con- 

 siders this to have been a mutilated species 

 of Oxytricha. The appearance of horns 

 arises from the anterior part of the body 

 being deeply notched. 



BIBL. Ehrenb. Infus. ; Dujardin, Infus. 

 p. 421. 



CERATIUM, Alb. and Sch. A genus of 

 Isariacei (Hyphomycetous Fungi), containing 

 an uncommon British plant, C. hydnoides, 

 which grows upon rotten wood as a tuft of 

 white prickle-like processes, bearing fila- 

 ments composed of strings of cells which 

 separate into conidia', large spores occur 

 among these, but their development is not 

 clear. The whole plant collapses ulti- 

 mately into a mucilaginous mass. 



BIBL. Berk. Hook. Br. Flor. ii. pt. 2. 

 329 ; Grev. Sc. Crypt. Fl. pi. 168. 



CERATIUM, Schrank. Dujardin retains 

 this name for three species of Peridinium 

 cornutum, tripos, sm&fusus. 



CERATODON, Bridel. A genus of Pot- 

 tiaceous Mosses. 



Ceratodon purpureus, Brid. = Didym. 

 purpureus, H. and Tayl. 



CERATONEIS, Ehr. A genus of Dia- 

 tomaceae. 



Mr. Smith places the British species in 

 other genera, thus : 



C. arcus = Eunotia arcus ; C. closterium 

 = Nitzschia cl. ; C. fasciola = Gyrosigma 

 (Pleurosigma, Sin.) fasc. ; C. gracilis = 

 Nitzschia tcenia ; C. longissima = Nitzschia 

 Urostrata. 



Kiitzing describes four other species ; but 

 they have not been satisfactorily examined. 



BIBL. Ehr. Ber. d. Berlin Ak. 1839, 

 p. 123, 1840 et seq. ; Kiitz. Bacill. and Sp. 

 Alg. -, Smith, Brit. Diat. 



CERATOPTERIS, Brongniart. A genus 

 of Parkerieseous Ferns. Exotic. The in- 

 rolled margin of the leaf similates an indu- 

 sium. 



CERCOMONAS. Duj A genus of Infu- 

 soria, of the family Monadina. 



