FENESTELLA. 171 



Remarks. — The type of Phillips's F. arthritica, var. y, is in the Museum of 

 Practical Geology, and came from Hope's Nose. No structure can be seen in it 

 except a coarse nodulation on the reverse of the branches ; but in that and in its 

 general character it is so similar to the present fossils that there is little doubt 

 that they are identical. It appears to be a flabellate form growing from a large 

 base of attachment. It is by no means so easy to say whether F. arthritica, 

 vars. a and /3, are the same species ; and if not, which should have the right to 

 precedence, for though his var. y ranks third in the text, it ranks first in the 

 Plate. Of his figures, 36 a and b evidently i-epresent his var. y, 36 c represents 

 his var. /3, and 36 e his var. a, which he himself calls "a variety." But the two 

 latter are not so clearly defined as the former, and possibly may never be satis- 

 factorily identified. Therefore we may fairly claim Phillips's name for the present 

 species, and leave the others to receive new names if they should ever be proved 

 distinct. 



Under the name Retepora antiqua, Goldfuss described a fossil which is not 

 very dissimilar, though differing by having smooth and rather stouter branches. 

 Its cells, size, and other features are unknown, and it seems hopeless to attempt 

 to identify it specifically. It is perfectly distinct from Gorgonia antiqua, Goldfuss 

 (which is the original of Lonsdale's and Phillips's F. antiqua, Goldfuss), though 

 it seems to have been in M'Coy's mind in defining the British species. Even, 

 therefore, if it were the same as our species, which is more than doubtful, it 

 would be only adding to the confusion to adopt Goldfuss's name ; and it may 

 be argued that, though R. antiqua comes before G. antiqua in Goldfuss's work, 

 yet the latter, having long ago been referred to Fenestella, has the priority in 

 that genus, and ought not to be ousted by another synchronous and indistinct 

 species of the same author. At present, however, there is no proof whatever of 

 the specific identity of R. antiqua with F. arthritica. 



The generic position of our species is not free from doubt. It appears to be 

 an aberrant form of Fenestella with an unusually high blade-like keel, but this 

 keel seems so remarkable as to suggest it may be a passage-form into some more 

 elaborated genus. In thin sections it has the appearance of a transparent wall 

 definitely bisecting the substance of the branches, and there is a possibility that 

 in none of the specimens its true summit has been preserved. 



I have had some difficulty in identifying the various prepared sections, though 

 I believe that all those figured belong to this species. One specimen, however, is 

 perplexing and perhaps doubtful. This is a shallow, flabellate frond (PI. XIX, 

 fig. 10), giving a beautiful natural section along the branch, and it seems to show 

 that the central keel, when perfect, was somewhat expanded at the top. 



Affinities. — This species seems very well characterised, and quite distinct from 

 any of the others that occur at Lummaton. 



