OF THE DESMIDIEJE. 



743 



spines projecting to each side. L. 1-770' ; 

 B. 1-580'*' to 1-636". I. 



10* Segments in f.v. with the opposite 

 lateral extremities tei'minating in one 

 or ttco elongate colourless 2^''oeesses 

 mostly divided at the apex ; and in e.v. 

 either tapering into a single process at 

 each angle, and furnished icith others 

 beticeen or above of a similar character 

 definite in mmiber, or the angles fur- 

 nished with two short processes side by 

 side and unaccompanied by others. 



t Segments at end view \vitli tlie addi- 

 tional processes more than one for each 

 angle^ and placed on the margin or 

 upper surface, and diverging laterally. 



S. furcatum (Breb.). — Segments 

 smooth, in f v. broadly elliptic, furnished 

 at each opposite lateral extremity with a 

 colom-less bifid process, and with six 

 others similar and divergent on external 

 margin (four only of which are usually 

 \'isible) ; e.v. with three acute angles, 

 each tapering into a terminal process, 

 and each bearing two others on the upper 

 surface, placed to each side, and project- 

 ing laterally. L. 1-860"; B. 1-900".= 

 Xanthidium furcatum (Ehr.), Astero- 

 xanthium furcatum (Kg.), A. bisenarium 

 (Kg.)? •aB.,L,F. 



S. senarmm (Ehr.). — Segments 

 smooth, in e.v. with three angles, each 

 temiinatiug in a short process tipped by 

 minute spines, and having six other short 

 forked processes on the margins, two at 

 each side and projecting laterally, and 

 six others on the ujoper surface, confluent 

 at their bases, divergent at their exti-e- 

 mities, and forked ; sides straight, (ii. 7.) 

 = Stephanoxanthiiim se^iarium (Kg.). 



S. eiistephanum (Ehr.). — Segments 

 gi'anulate, in e.v. with three angles, each 

 terminating in a short process tipped by 

 minute spines, without latei'al processes, 

 but %vith six others confluent at their 

 bases on the upper sm-face, divergent and 

 forked, (ii. S.) = Stephanoxanthium euste- 

 phamnn (Kg.). U.S.A. 



S. Ehrenbergii (Coy&q). — " Corpuscles 

 par paire, vus de cote, ovale s ; vus d'en 

 haut, triangulaires, munis de six ap- 

 pendices terminaux et lateraiLx, et de 

 deux autres appendices centraux, qui 

 sont coui'ts, blancs, en fomx-hette, mais a 

 pointes divergentes " (Corda, ' Obs. 

 Micr. des Animalcules de Carlsbad,' 

 1840). In Corda's figure the f. v. is 

 somewhat like that of S. furcatum. The 

 segments are broadly fusiform, the pro- 



cesses are aU very short and stout, and 

 the bifiu'cations very divergent (formed 

 indeed somewhat like the tail of a Jish). 

 =Xanthidium Ehrenbergii (Corda, /. c). 

 S. ai'ticidatwm (Corda). — " Corpuscles 

 ovales, par paii*e, munis aux deux bouts 

 d\m appendice a deux cellules, qui se 

 divise encore en fonue de fom-chette, et 

 lateralement en deux appendices plus 

 longs a quatre cellules, et une pointe en 

 fom'chette. Sur les deux cotes plats, se 

 trouveut deux protuberances trans- 

 versales, egalement pom-vues de deux 

 allongements cellulau-es en fourchette " 

 (Corda, I. c). In Corda's figures the seg- 

 ments in f.v. are elliptic, the processes 

 stout, elongate, transversely striated (by 

 rows of granules?), bifurcate, the bifurca- 

 tions recmned. = X urticulatum (Corda). 

 Neither of the figm-es of the foregoing is 

 explanatory ; both, however, seem to be 

 distinct species. 



2t Segments with the additional pro- 

 cesses one for each angle, and placed 

 on the upper sui-face immediately 

 above those terminating the angles. 

 S. furcigerum (Breb.). — Segments in 

 f. V. twice as broad as long, separated by 

 a deep constriction, rough with pearly 

 granules, terminating at each side in two 

 elongate, stout processes, bifid at the apex, 

 placed one above the other, the inferior 

 horizontal, the superior directed ob- 

 liquely outwards and divergent, both 

 having the granules thereon in trans- 

 verse lines ; e. v. with three or four 

 angles, each extremity terminating in a 

 process and having the other immedi- 

 ately above it on the upper sui-face, sides 

 concave at the centre. L. 1-333"; B. 

 1-357" inch processes, (in. 32, e.v. 33.) 

 — Bidymocladonfurcigerus (Ralfs), Aste- 

 roxanthium furcigetmm (Kg.), Xanthi- 

 dium coronatum (Ehr.) ?, A. coronatum 

 (Kg.) ? G.B., I., F., G., U.S.A. 



S. longispinum (Bail. sp.). — Segments 

 in f. V. triangular, trimcate on outer mar- 

 gin, smooth, terminating at each side in 

 two much elongated stout processes, sub- 

 acute at the apex, placed one above the 

 other, divergent ; e. v. with three angles, 

 each exti'emity tenuinated by a process 

 and having the other immediately above 

 it on the upper surface, side straight. = 

 Didymocladon longispinum (Bailev). 

 U.S.A. 



3t Segments with two processes from 

 each angle placed side by side. 

 S. l(Bve (Ralfs). — Segments in f. v. ex- 

 ternally lunate or somewhat cuneate, with 



