177 



at left a sporangium with a single small sterile cell at the top and at right an 

 apparently terminal sporangium. There is no doubt that the sporangia here men- 

 tioned are transformed cells of the filaments in which they are situated; this is 

 more doubtful in the case represented in 

 fig. 95 /, where the sporangium has the 

 appearance of being lateral, but as it has 

 been found in the same crust as those 

 figured in fig. 95 F—H, it must be sup- 

 posed that it has really been terminal. 

 The single sporangia are 2 to 3 times as 

 long as broad, 26 — 50 /7. long, 11 — 14 // 

 broad. Their great length depends pro- 

 bably on their terminal or subterminal 

 place, which permits them to develop 

 unhindered by sporangia or sterile cells 

 lying above. In some crusts only such 

 lengthened sporangia, singly or in pairs, 

 are found; in others they are found in 

 company with the ordinary seriate ones, 

 as a rule, however, in different parts of 

 the frond. By this fact it is shown that 

 the two kinds of sporangia really belong 

 to the same species. Single sporangia 

 have been met with in three places in 

 spring (Ks: Hastens Grund; Sa: Ronnen 

 in Begtrup Vig and Lb: off Middelfart). 



There is no resemblance between 

 the single sporangia of this species and 

 those of Petrocelis cruenta J. Ag., which 

 are strictly intercalary and globular (comp. 

 Le JoLis Alg. mar. Cherb. pi. Ill, fig. 4). 



In specimens gathered in November 

 in the Great Belt I have found spores 

 germinating in the seriate sporangia (fig. 

 95 E). The spores were divided by va- 

 riously orientated walls and some of the 

 uppermost resulting cells were growing 

 out upwards into filaments. 



The antheridia arise in the upper 

 part of the vertical filaments, where they 

 form small lateral bushes, rather similar to those of Cruoria. They are borne on 

 the upper end of small, usually unicellular, more rarely bicellular, branchlets, two 



Fig. 95. 



Petrocelis Hennediji. Vertical filaments witli tetrasporangia. 

 A, six still undivided sporangia, November B and C, 

 ripe sporangia, July. D, filament with two sporangia 

 only, April. E, tetraspOres germinating in the sporangia, 

 April. F ' I, from Begtrup Vig. May, F with seriate spor- 

 angia, G with subterminal, H and / apparentlj' with 

 terminal sporangia (in / possibly lateral ?). A,D,E,G,H 

 390:1 C, C,F,/, 300: 1. 



D. K. I). Vldeii.sli. Selsk.Slu-., 7. H;elike, iiatui videiisk. og matliem. Aid. VII. 



23 



