OUTER PERIDIUM OF BROOMETA. 313 
woven hyphe similar to those described by Mr. Berkeley a 
forming the stroma, only more densely compaeted together. 
It will be remembered that in Geaster, the nearest ally of this 
plant, the individuals appear singly, and each is furnished with 
both peridia, the outer one of which splits perpendicularly 
along definite lines of fission, each segment folding back and 
the whole forming the stellate support. 
DESCRIPTION OF PLATE XXIX. 
Fig. 1. View from above, showing:—«, remains of outer peridium; 6, inner 
peridia. 
2. Vertical section :—a, outer peridium ; 4, inner peridia. 
3. View of inner peridia, b, with fragment of outer peridium, a, still 
adhering, X 2. 
4. Spores, x 780 diam. After Mr. Berkeley. 
5. View of mature inner peridia when outer peridium has disappeared. 
After Mr. Berkeley. 
On the Diatoms collected during thé Arctic Expedition of Sir 
George Nares. By P. T. OrzYz, Professor of Chemistry in 
the University, Upsala. (Communicated by Sir J. D. 
Hooxzn, V.-Pres. L.S.) 
[Read April 9, 1883.] 
TuHnovauH the kindness of Prof. Oliver I have got for examina- 
tion several samples containing diatoms, and collected during the 
Arctic Expedition of Sir George Nares. Among them were only 
four gatherings containing diatoms in such number that I was 
able to subject them to the usual cleaning process necessary for 
getting the valves in a state suitable for examination. Among 
these four samples one from Cape Sabine (lat. 78° 40' N.) con- 
tained freshwater species, the other three, from Bessel’s Bay, 
Mushroom Point, and Discovery Bay, contained marine forms. 
The sample from Discovery Bay, which had been collected on the 
ice, consisted almost exclusively of a single species, Melosira 
nummuloides, var. hyperborea, Grun., but contained also sparingly 
some other diatoms. 
The alge collected during the expedition have already been 
examined by Dr. Dickie*, who also has given alist of the diatoms. 
The freshwater species found in the gathering from Cape Sabine 
were the following:— 
* Journ. Linn. Soc., Bot. (1878) vol. xvii. p. 6. 
LINN. JOURN.—BOTANY, VOL. XX. 2c 
