BY G. I. PLAYFAIR. . 493- 



Plate xii. 



Fig. 1. — Doc. trahecida var. Ekr enhergii (Breh.) (a) + a baailum-sha,ped 

 semicell (b) (lat.bas.21) showing that the chloroplast alters from an 

 incomplete tube in var. bacuhim to parietal fillets in var. Ehren- 

 bergii as the cell develops. The lower portion of the endochrome 

 is still undivided in (a), and the apical part in (b) shows the 

 original axillary lamina, Pleurota'nium is only the adult form of 

 Docidium. ( x 347). 



Fig.2. — Doc. trabeculav&Ti:. baculnm (Breh.) showing the tubular parietal 

 chloroplast ( x 463). 



Fig.3. — Doc. trabecida var. bac^dicm (h) + a. younger form in which the basal 

 grannies are replaced by fainter plies not visible beyond the margin. 

 There is thus no essential difference between the granules and the 



plieas (x463). 



Fig. 4. — Doc. tr abecula va.r. &rtCM?o«Ze.s (Roy & Bissett), forma ( x 347). A 

 curious form, uniting the shape af var. baculoides, the basal plicae 

 of var. baculum and the size(lat.bas, 18) and apical granules of var. 

 Eh7'enbergii, 



Fig.5. ~Z>oc. trabecida vav. Ehrenbergii {Br 6h.), forma (x347). Basal por- 

 tion only, to show the faint plicae discernible on either side of the 

 isthmus. 



Fig.6. — Doc. trabecida var. pygmcnmn, n.var. ( x463). 



Fig.7. — Doc.trabecida{\>) + \&r. truncatum, a living specimen, showing the- 

 " cellular " arrangement of the protoplasm ( x 347). 



Fig.8. — Apex of forms of D. trabecida, viz., var. Ehrenbergii, vsux.baculuviy 

 and VB.i\ pygiyio'um, all found together in one gathering(No.l09). 

 The cell-wall of all these was strongly punctato-scrobiculate, as 

 shown; at the ends the pores could plainly be seen running through, 

 the incrassate membrane (x463). 



Fig.9. — St. sexangulare Bulnh., var. 2)Iaii/ceritm(Josh..) (x463). 



Fig.lO. — ,, var. dentatum, n.var. (x463). 



Fig.ll. — ,, var. j/emwesceH-s, n.var. ( X 463). 



Fig.l2. — ,, var. subglabrum W. & G. S. West, forma ( x 463). 



Fig.l3. — ,, var. n-s/ferMm, n.var. ( x 463). 



Fig. 14.— ,, type(x463). 



Figs. 9-14 show the development of the upper processes in St. sexavgidare. 



Fig. 15. — St. orbicidare var. 7nufinvm{Brtih.) ( x 695). 



Fig.l6. — ,, var. gramdosum, n.var. (a) end ( x 695). 



Fig.l7. — ,, var. acnleatum, n.var. (a) end ( x 695). 



Fig. 18.— ,, var. bifarium{'NoT(\.) f. (a) end ( x 695). 



Fig.l9. — St, orb. var. bijarium f.,(a) + var. aggeratiwi Playf., forma (b)y 

 (x463). 



Fig.20. — St. orb. v&v. for^cidatumiLund.), forma ( x 695). 



