OF THE DESMIDlEiE. 



735 



Sporangium orbicular, spinous ; spines 

 short, stout, conical. L. 1-498" to 1-454" ; 

 B. 1-7 50". =Penium orhicuJatum (Kg.). 

 Ct.B., f. 



2 1 Frond smooth. 



C. moniUforme (Ralfs). — Frond mi- 

 nute, in f. V. twice as long as broad ; 

 constriction deep ; segments spherical, 

 smooth ; e. v. circular. L. 1-617" ; B. 

 1-1131". = Tessarthroma monilifonnis 

 (Turp.), Tessarthra tnoniUformis (Ehr.). 

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



C. connatum (Breb.). — Frond large, 

 in f. V. about one-half longer than broad ; 

 constriction shallow ; segments about two- 

 thirds of a circle, coa^vsely pimctate, and 

 with a distinct, sometimes striated, bor- 

 der; e.v. circidar. L. 1-285"; B. 1-1155". 

 = Dysphinctium Meneghinianum (Nag.). 

 G.B., F., U.S.A. 



C. Cucurbita (Breb.). — Frond in f. v. 

 about tAvice as long as broad ; constric- 

 tion a shallow groove ; segments sub- 

 cylindrical, or somewhat oval, with 

 rounded ends ; e. v. circular ; e. f. punc- 

 tate, the 2^iinctxi scattered. L. 1-586" ; 

 B. 1-1155". =Pewmw clandestinum (Kg.). 

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



C. Talangula (Breb.). — Frond in f. v. 

 about two and a half times as long as 

 broad ; constriction a shallow groove ; 

 segments cylindrical ; ends obtuse ; e. v. 

 circular ; e. f. minutely punctate, the 

 puncta arranged in transverse lines. F. 



C. ? cruciferum (De Barj). — Frond 

 minute, in f. v. about tmce as long as 

 broad ; constriction an extremely shallow 

 groove; segments subcylindrical ; ends 

 broadly rounded ; endochrome composed 

 of four broad plates cutting each other at 

 right angles ; e. v. cii'cular, endochrome 

 cruciform) e. f. not punctate. L. 1-143'"; 

 B. 1-287"'. G. 



C. Thwaitesii (Balfs). — Frond in f. v. 

 two or three times longer than broad; 

 constriction a very shallow groove ; seg- 

 ments subcylindrical, with rounded ends ; 



endochrome scattered ; e. v. circular, or 

 very slightly compressed; e.f. not punctate, 

 or puncta very indistinct. L. 1-357"; 

 B. 1-801". = Penium crassiusculum (De 

 Bary) ? G.B., F., G., U.S.A. 



C. curtum (Breb.). — Frond in f. v. 

 rather more than twice as long as broad ; 

 constriction very shallow; segments at- 

 tenuated and rounded at ends ; endochrome 

 in fillets ; e. v. circular, endochrome ra- 

 diate. L. 1-465" ; B, 1-1064". = Penium 

 curtum (Breb., Kg.), Dysphinctium Pege- 

 lianum (Nag.) ? G.B., F., G. 



C. attenuatum (Breb.). — Frond in f. v. 

 fusiform, three, or sometimes four, times 

 longer than broad ; constriction very 

 shallow ; segments coniccd, rapidly at- 

 tenuated, ends angular, obtuse ; e. v. cir- 

 cular ; e. f. punctate. L. 1-420" ; B. 

 1-1099" to 1-1068". G.B., F. 



C. parvulum (Breb.). — Frond minute, 

 in f. V. ovato -elliptic, about one and a 

 half times longer than broad ; central 

 constriction a very shallow groove ; seg- 

 ments tapering, ends broadly rotundato- 

 truncate ; e. f. 7iot punctate. F. 



C. turgidum (Breb.). — Frond very 

 large, in f. v. oval, turgid, rather more 

 than twice as long as broad ; constriction 

 a shallow sinus ; segments somewhat 

 tapering, broadly rounded ; e. v. circular ; 

 e. f. pimctate. L. 1-126"; B. 1-249". 

 = Pleurotcenium turqidum (De Bary). 

 G.B.,F.,G. ^ ^^ 



0. De Baryi (nobis). — Frond in f. v. 

 about twice as long as broad ; constric- 

 tion a ivide shallow notch ; segments 

 cylindrical, with broadly rounded ends ; 

 endochrome arranged in parietal itidented 

 bands ; e. v. cu-cular ; e. f. minutely punc- 

 tate or pimcta absent. = Pleurotcenium 

 Cosmarioides (De Baiy). G. 



With gi'eat deference, we place the 

 above species here, as described by 

 M. de Bary, coinciding with M. de Bre- 

 bisson in thinking the disposition of the 

 endochrome not sufficiently constant to 

 form the genus Pleiu'otaenium. 



Genus XANTHIDIUM (Ehr.). — Frond deeply constricted ; segments 

 broader than long, compressed, entire, spinous, having a circidar, cylindrical 

 or conical projection on hath surfaces near the centre, which is tuberculated or 

 dentate, or entii'e ; end \iew elliptic. 



nated by three or four diverging points ; 

 central projections cylindrical, trimcate, 

 the border dentate ; e. f. punctate. " Spo- 

 rangium large, orbicular, with depressed 



* Spines divided at the apex. 



Xanthidium armatum (Breb.). — 

 Frond large, in f. v. twice as long as 

 broad ; constriction deep, linear ; seg- 

 ments broadest at the base ; ends rounded 

 or somewhat truncate ; sptines in jjairs, 

 principaUy marginal, short, stout, termi- 



tubercles ; perhaps immature " (Ralfs). 

 L. 1-180"; B. 1-270". (i. 27, 28.) = 

 Zygoxanthium Echinus (Kg.). G.B., I., 

 F., G., U.S.A. 



