or THE DESMIDIEiE. 



747 



nearly straight, cylindrical, not tapering, 

 up2)er and lower margin equally and hut 

 very slightly curved, ends ohtusely rounded; 

 large granules, in a single series ; e. f. 

 smooth. F. 



C. Amhlyonema (Ehr.). — Frond stout, 

 very long, twenty to twenty-five times 

 as long as broad, slightly curved, scarcely 

 tapei'ing,\i^T^ev and lower margins equally 

 and but gently cur^^ed ; ends broadly 

 rounded; e. f. smooth. U.S.A. 



2 * Frond tapering, having the curvature 

 slight : loiver margin straight or very 

 slightly concave, and slightly inclined 

 upwards towards the rounded or sub- 

 acute ends; e. f. icith or ivithout lon- 

 gitudinal strice. 



C. Lunida (Ehr.). — Frond large, stout, 

 five or six times as long as broad, semi- 

 lunate, iip^^er margin very convex, lower 

 nearly straight, someivhat inclined upwards 

 towards the obtuse broadly rounded ends; 

 endochrome with the large granules 

 numerous, scattered, fillets several, di- 

 stinct ; e. f. colomiess, without mark- 

 ings, central sutm^e not evident. L. 

 1-62"; B. 1-330". = Vibrio Lunida 

 (Miiller), Bacillaria Lunula (Schrank), 

 Lunulina vulgaris (Bory). G.B., F., I., 

 G., Italy, U.'SA., Mexico. 



C. acerosum (Ehr.). — Frond slender, 

 six to fifteen times as long as broad, 

 linear-lanceolate, gradually tapering, 

 upper margin slightly convex, the lower 

 nearly straight, slightly inclined upwards 

 at the conical ends ; large gi'anules in a 

 single central longitudinal series ; fillets 

 several, distinct ; e. f. colomiess, very 

 faintlv stiiated, central suture evident. 

 L. 1-70" to 1-58" ; B. 1-1103" to 1-510". 

 Sporangimn orbicular, smooth, placed 

 between the dehiscing deciduous empty 

 fronds. = Vibrio acerosus (Schi"ank). 

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



C. lanceolatum (Kg.). — Frond stouter 

 than C. acerosum, six to ten times longer 

 than broad, semilanceolate, gradually ta- 

 pering ; upper margin convex, lower 

 nearly straight, inclined upwards to- 

 wards the tajiej-ing subacute ends ; large 

 granules in a single central series ; fillets 

 several, distinct ; e. f. colourless, usually 

 without markings, sometimes faintly 

 striated, central suture evident. L. 

 1-64"; B. 1-453". = CymbeUa Hopkirkvi 

 (Moore). G.B., I., R, G., U.S.A. 



C. turgidum (Ehr.). — Frond stout, 

 eight to twelve times as long as broad, 

 semilanceolate, slightly tapering., more 

 curved than either of the preceding, 



upper margin convex, tvith a depression 

 near each extremity, lower margin con- 

 cave, inclined upwards towards the 

 rounded ends ; large granules, in a single 

 longitudinal series ; fillets several ; e. f. 

 reddish, longitudinal strice close, distinct, 

 central sutm*e evident. L. 1-39" ; B. 

 1-370". (m. 40.) = a decussatum (Kg.) ? 

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



C. prcelongum (Breb.). — Frond very 

 slender, extremely long, thirty-five to 

 forty times as long as broad, slightly 

 curved, vei-y gradually tapering; upper 

 margin slightly convex, with a depres- 

 sion near each extremity ; lower concave, 

 inclined upwards towards the roimded 

 ends ; large gTanules in a single series ; 

 e. f. colourless, without markings. F. 



C. quadrangulare (Corda). — Frond 

 very slender, twenty-five to thirty times 

 as long as broad, slightly curved, gra- 

 dually tapering, quadrangular, except at 

 the extremities, one of the angles forming 

 a p>rominent longitudinal median line ; 

 upper margin equally convex, lower con- 

 cave, very slightly inclined upwards at the 

 blimt ends ; e. f colourless, smooth. G. 



3 * Frond tapering, the lower margin 

 concave, often tvith a central injiation, 

 and inclined dowmvards toicards the 

 rounded or subacute ends ; e. f. ivithout 

 markings. 



t Frond slender, curvature very slight. 



C. strigosum (Breb.). — Frond slender, 

 twelve or fifteen times as long as broad, 

 nearly straight, but someivhat curved down- 

 ivards towards the attenuated extremities : 

 upper margin slightly convex, lower 

 concave tvith a gentle central iti/lation ; 

 ends acute ; large granules in a single 

 series ; e. f colomiess, without striae. 

 Sporangium orbicular, smooth, placed 

 between the shortly deciduous empty 

 fronds, which conjugate soon after divi- 

 sion, so that two of the empty segments 

 are considerably shorter than the other 

 two. F. _ 



C. macilenttun (Breb.). — Frond very 

 slender, sublinear, twenty-five or thirty 

 times as long as broad, slightly and 

 very gradually cm'ved, somewhat taper- 

 ing ; upper margin slightly convex, lower 

 slightly concave ; ends someivhat blunt ; 

 large gTanules, in a single series; e. f. 

 colom-less, without striae. Sporangium 

 orbicular, placed between the for some 

 time persistent empty fr-onds, which 

 conjugate, as in last, soon after divi- 

 sion. F. 



