Plumularia. 
Z. PIYDROIDA. 
145 
I have a specimen of PI. cristata gathered in Cork Bay, and present- 
ed to me by J. V. Thompson, Esq.,* which is nearly 3 inches in height, 
spreading laterally, the rachis divided in a regular dichotomous man- 
ner, and rough or muricated on one side, wherever it is naked of 
pinnae. The vesicles have from 7 to 9 crested ribs with a spinous 
dorsal keel. The roughness of the rachis is produced by the remains 
of the deciduous pinnae. I give a figure of this specimen, (Plate XX. 
Fig. 1,) as an additional proof that little reliance can be placed on ex- 
ternal habit as a character in determining the species of this order. 
3. P. pennatula, plumous , the pinna opposite ; cells in a 
close row , cup ’like with an unequally crenated margin , support- 
ed on the under side by a lengthened incurved spinous process . 
Montagu. 
Plate XVIII. Fig. 1, 2. 
Sertularia pennatula, Ellis and Soland. Zooph. 56, tab. 7, fig. 1, 2. Bose, 
Vers, iii. 114. Fleming in Edin. Phil- Journ. ii. 83 Aglaophenia 
pennatula, Lamour. Cor. Flex. 168. Corail. 74. Plumularia penna- 
tula, Lam. Anim. s. Vert. ii. 128. 2de edit. ii. 165. Flem. Brit. 
Anim. 546. La P. pennatule, Blainv. Actinolog. 478. 
Hah. Coast of Devonshire, rare, Mr Montagu. 
“ This coralline is as remarkable for the elegance of its form, as its 
likeness to the feather of a pen/' Specimens from the seas of tropi- 
cal climates are from 5 to 6 inches high, but my British specimen, 
which I owe to the liberality of J. E. Gray, Esq., is scarcely one inch 
and a half. The polypidom rises from implexed tubular fibres : the 
lower portion of the cylindrical jointed rachis is naked, the upper 
pennate and gracefully proportioned. The cells are small with a 
waved margin and a little spine on each side, and they are seated in 
the axil of a long tubular incurved process which rises much above 
them. Lamouroux has conjectured that the PI. pennatula of Flem- 
ing is only a repetition of PI. myriophyllum ; and Milne- Edwards 
refers it to PI. cristata. I cannot see the slightest foundation for 
these suspicions. 
4. P. pinnata, stem plumous , the pinna cdternate ; cells ra- 
ther distant , one on each internode , campanulate , leaning , the 
mouth entire ; vesicles obpyriform , strongly toothed above , Dil- 
lenius. # 
Plate XVII. Fig. 4, 5. 
* Born in 1687 at Darmstadt in Germany ; came to England in 1721 ; and died 
at Oxford in 1747. He was the first Professor of Botany there, and has not been 
equalled in celebrity by any successor. It is unnecessary to give particulars of 
K 
