82 BOTANICAL RESULTS OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 



gatis sparsis cartilagine hyalina immersis hie illic filamento tenui inter se conjunctis ; 

 cellulis subcorticalibus minoribus paucis rotundatis, corticalibus elongatis angustis 

 (20-25 M x 4 M) congestis monostromaticis ; omnibus protoplasmate granuloso instructis. 

 (Figs. 18, 19.) 



Habitat. Scotia Bay, South Orkneys, March 25, 1903. 



This specimen consists of a broad, thickish, cartilaginous frond, recalling Iridsea, much 

 rent and irregular in outline, about 23 cm. in length and width. No point of attach- 

 ment is to be distinguished, and the thallus is ragged and slit at the margin and in 

 the body of the frond something like Kiitzing's figure of Iridsea cornea (Tab. Pliyc., 

 xvii. tab. 20). Neither cystocarps nor tetraspores are present. The surface is smooth, 

 and in some parts the cortex has been eroded, but in others it is quite uninjured. In 

 transverse sections the interior of the thallus is seen to be composed of fairly large 

 irregular cells, rotundato-angulate or elongated more or less perpendicularly to the 

 surface, spaced out and embedded in a hyaline cartilaginous matrix. All the cells are 

 lined with a granular protoplasm, and here and there show distinct thin strands of 

 protoplasm from cell to cell. This broad interior tissue forms the greater part of the 

 thallus, and is bordered on either side by a thin band of much smaller round cells, 

 closer together and abutting on the cortex. The cortex is composed of a row of long, 

 narrow, closely-packed vertical cells. There is no medullary stratum of filaments. 



In attempting to determine the systematic position of this plant, we have examined 

 innumerable microscopic preparations of various genera without finding any structure 

 resembling that of our plant. The total absence of a filamentous medulla prevents it 

 from being placed in Kallymenia or Euhymenia, which otherwise it somewhat resembles. 

 We are very much puzzled by Reinsch's Kallymenia reniformis f. carnosa (Meeresalgenfl. 

 v. Sud Georgien, p. 394), the medullary parenchyma of which he describes as a homo- 

 geneous tissue of larger cells with wider lumen than in K. reniformis, and packed with 

 starchy contents. He gives no figure, and his description is too incomplete to enable 

 us to decide whether, or how far, his plant approaches ours. He states that his plant 

 has a very different structure from typical K. reniformis, except for its cortex. Our 

 plant differs from K. reniformis in having its cortical cells vertically elongate, and not 

 rotundate ; and its interior cells often elongate perpendicularly, and not parallel to 

 the surface of the frond. Though unable to indicate the genus to which this Scotia 

 specimen belongs, we record our observations in the hope that fertile material gathered 

 by one of the other Antarctic expeditions may give the clue to its identity. 



Since the above was written, it has occurred to us that this specimen might possibly 

 be an aged incrassate plant of Gracilaria simplex. But as the material is no longer 

 in our possession, we are unable to put this idea to the test. 



