DESCRIPTIVE REMARKS. XI 
coverer,* defining two species, O. antigua and radiata, examples of 
which are figured, on Platei., figs. 1 and 2. Several years later, Dr. 
Kinahan, who had collected better specimens, reviewed and figured 
them, giving scientific descriptions, with remarks respecting their affi- 
nities. + 
The position these Fossils should occupy in the scale of organic life 
has been the subject of much discussion: by some paleontologists they 
are considered to be plants ; others believe them to be allied to Grapto- 
lites. We prefer to leave them in the place originally assigned to them 
by Professor Forbes, because there appears to be no tangible ground 
for altering his opinion as to their alliance, and they resemble suffi- 
ciently close in their general appearance several of the Sertularian 
Zoophytes (commonly known as Corallines), particularly the arbores- 
cent forms of Sertularia cupressina and argentea{ (woodcut, fig. 1, a), 
which may be compared with O. antigua. This species may be also 
compared with Celluluria avicularia,§ a Polyzoan of the family Escha- 
ride, woodcut, fig. 1, 6; and the frondose or bushy variety of one of 
the Escharide, Cellularia plumosa|| (woodcut, fig. 1,¢, d), with O.radiata. 
If plants, they could only have been Nullipores or Algee, and in that 
Fig. 1.—Recent Hydrozoa, &c., to compare with Oldhamia. 
All the figures are of the natural size. 
a. Sertularia argentea, upper portion. 
8. Cellularia avicularia. 
ce. d. Cellularia plumosa. . 
* Journ. Geol. Soc. of Dublin, vol. iv., p. 20 (1848). 
+ Trans. Royal Irish Acad., vol. xxiii. (1858). 
t Johnston’s British Zoophytes, vol. i., pl. xiv., f, 3; and vol. ii., pl. xv., xvi. 
Ibid., pl. lxiii., figs. 7, 8. 
|| Ibid., pl. Ixi., figs. 1-5. 
