a name designed to express a peculiarity of growth, its favourite 
habitat being the flat bottoms of shallow rock-pools, where it is 
generally half buried in sand. Dr. Greville, who first described 
and figured it in his Cryptogamic Flora, gave it the name erectus, 
from another of its distinguishing characters, the peculiarly up- 
right and rigid frond. When in perfect fructification it is easily 
recognised ; the clustered tubercles and the lanceolate pod-lke 
tips bemg both very striking characteristics. But barren speci- 
mens are exceedingly hike, except in colour, young plants of G. 
confervoides, from which their greater simplicity, and more rigid 
substance, and erect growth, alone distinguish them. It is 
proper to mention that the Orkney specimens above noticed are 
without fruit ; and, therefore, notwithstanding the perfect resem- 
blance of their frond to Devonshire individuals, some doubt may 
rest upon their identity. In my own judgement they do belong 
to this species ; but I am informed that another very competent 
authority is not satisfied; nor until fertile plants shall have been 
procured is it possible to determine which opinion is correct. The 
French specimen, communicated by M. Lenormand, is also 
barren, and is therefore equally doubtful. 
Fig. 1. GRacrLarta ERECTA, with pods. 2. With tubercles :—both of the natu- 
ral size. 3. Pods. 4. Transverse section of the surface of a pod, showing 
imbedded tetraspores. 5. A tetraspore. 6. Branches with tubercles. 7. 
Transverse section of a branch and a tubercle :—all more or less magnified. 
