10 ANTONY GEPP AND ETHEL S. GEPP. 



crassse, inferne in stipitem plus minusve sensim augustatum, 1-3 cm. longum 

 attenuate, stratis duobus context* cellulis interioribus rotundato-angulatis magnis 

 2-3 seriatis pachyderinis (frondis sterilis majoribus maxime leptodermis collabcntibus 

 submonostromaticis) ; cellulis corticalibus filamenta ramosa verticalia efficientibus, 

 tetrasporangia magna cruciatim divisa foventibus (frondis sterilis majoribus mono- 

 stromaticis). 



Off Cape Wadsworth, Coulman Island. 



Geogr. Distr. South Orkneys. 



This species is represented in the ' Discovery ' collections by one specimen only, a 

 single thin dried frond 22 '5 cm. long by about 1'5 cm. broad at its widest part. 

 Blunt and incomplete at apex, it tapers very gradually down to its attenuated stalk- 

 like base. This frond is quite sterile, and owing to the collapsed condition of its cells 

 as the result of drying, was not in itself sufficient for determination, for we altogether 

 failed to make the cells swell out again. Fortunately we found in the ' Scotia ' 

 collection from the South Orkney Islands two specimens, which clearly belong to the 

 same species, and being preserved in spirit, and uncrushed, revealed to us the interior 

 tissue in its natural condition. These ' Scotia ' specimens were also sterile, and we 

 described them under the name Leptosarca simplex (loc. cit.). Subsequently we 

 received a more complete plant, also from the S. Orkneys, which with a few other algae 

 had been overlooked in the ' Scotia,' until she was cleared out previous to being sold. 

 This plant bore ten fronds, some sterile, others tetrasporiferous. The two kinds of 

 frond exhibited differences of structure, the sterile being characterised by an internal 

 layer of large, extremely thin-walled cells, bounded by a monostromatic cortex, as 

 described for Leptosarca (loc. cit.}, while the sporiferous fronds with their large cruciate 

 tetraspores, thicker-walled internal cells and pluristromatic cortex compelled us to 

 transfer this species to Gracilaria, of which genus it should perhaps form a new section. 



9. GRACILARIA DUMONTIOIDES. 



(Plates III. and IV., figs. 17-20.) 



ffalosaecion ditmon/ioides Harv. ex Dickie, Journ. Linn. Soc. IX. (1867), p. 239 (noinen tantum). 

 Leptosarca dumontioides nob. in Journal of Botany, April, 1005, p. 108 (noinen tantum). 



Frons (vetusta incompleta) linearis, 6 5 longa, 4 mm. lata, complanata, membra- 

 nacea, prolificationes plurimas, intervallis irregularibus circ. 4 mm. latis invicem 

 separatas, maxime e marginibus ambobus emittens ; prolificationes 4-15 cm. longae 

 infra medium valde attenuatse tune sensim sursum expanses vel anguste lineares 4mm. 

 latae simplices vel cuneato- lineares latiores apiccm versus dichotomy, ramis vaklc 

 divergentibus. Color rosaceo-ruber. Cystocarpia et tetrasporangia ignota. 



Northumberland Sound, 76 N. lat., July 1853, leg. D. Lyall (fig. 20); Cape 

 Adare, 72 S. lat., February 24, 1904 (fig. 17). 



The only Antarctic specimen (fig. 17) which we have seen consists of a scrap of 

 an old frond, destitute of base and apex, encrusted by a zoophyte, and bearing laterally 



