982 G. W. SHRUBSOLE ON THE BRITISH 
ternal network is keeled and poriferous, as in Fvnestella, indeed 
resembles Fenestella membranacea.” 'To complete the evidence as to 
the connexion of Hemitrypa with Fenestella, W. H. Baily says of 
Fenestella membranacea, Phill., that ‘it exhibits impressions cor- 
responding with the condition of the fossil named Hemitrypa hiber- 
nica, M‘Coy.” Lonsdale, an early worker among the Polyzoa, has 
something to the point. Writing, in 1844, of Hemitrypa sewangula*, 
from Van Diemen’s Land, he says of it “ that it is not merely ‘ like 
some Fvnestella, but it possesses all the essential characters of that 
genus, and is believed to be a fragment of Fenestella fossula, Lonsd.” 7. 
Then he goes on to say, “‘ Of the true nature of the external net- 
work no opinion is ventured. ‘That it was a parasite, little doubt is 
entertained; and the interesting agreement between the space 
occupied by the double row of meshes and that of the parallel 
branches of the Fenestella arises apparently from the latter having 
afforded suitable base-lines for attachment.” There can be no doubt 
that the interior portion of Hemitrypa hibernica is a true Fenestella ; 
nor need we be in any doubt as to the species. Only one, Fenestella 
membranaced, Phill., has a conical base. The difficulty has always 
been the external sheath. It is important to mention that the same 
form is parasitic on brachiopods and crinoids, as well as Fenestella. 
Its connexion therefore with Venestclla is accidental and not . 
structural. It is without doubt a small coral common to the 
limestone, very similar to Mlustra palmata, M‘Coy t, the empty 
calices of which cover over and conceal the Fenestella beneath. 
Hemitrypa, as we have seen, has Kenestella membranacea, Phill., for 
the groundwork and a microscopie coral er polyzoon for the super- 
structure. 
Prof, M‘Coy has a note to the effect that “ Hemitrypa hibernica, 
M‘Coy, is possibly only the perfect state of Kenestella”§. We have 
seen that Actinostoma, and not Hemitrypa, furnishes the true type 
of the genus enestella. 
It is perhaps best to retain the name of Fenestella membranacea 
given to this species by Phillips; otherwise, from its unique form, it 
might well be distinguished as Fenestella carbonaria. 
The remainder of the Carboniferous species of MFenestella (six in 
number) are of doubtful character. Of Fenestella intertexta, Portl.||, 
it is enough to say that it has none of the characteristic marks of 
the genus. It is not a Fenestella. On the other hand, Gorgonia 
regularis, Portl.{], from the Silurian, is a true M Giestolla.: ; and the 
description, which is exceedingly true of Fenestella growth, is as 
follows :—‘‘ Grows from a central attachment into a circular flat- 
tened expansion. The stems are slightly branched, wiry, rather 
distant, and united by regular dissepiments.” 
* Darwin’s 2nd Voy. Beagle, pt. 2 4 p- 167. 
Ar Darwin's 2nd. Voy. Beagle, pt. 2, p. 168. 
+t M‘Coy’s Syn. Carb. Foss. Treland, pl. 26. fig. 14. 
§ M‘Coy’s Syn. Carb. Foss. Ireland, p- 205. 
I Geol. Londonderry, p- 324, pl, xxii A. fig. 3 
* Ibid, p. 323, pl. xx, fig. 6, 
