164 
VINE: CAKBONIFEEOUS POLYZOA. 
given the larger, and more general descriptions of Mr. Shrubsole 
which are founded upon a large suit of Carboniferous Fenestella, and 
from very wide localities. 
Genus Fenestella, Lonsdale. 
Zoarium, a calcareous reticulate expansion, either flat, conical, 
or cup-shaped, formed of slender bifurcating branches (interstices), 
poriferous on one face, connected by non -poriferous bars (dissepi- 
ments), forming an open network. Zowcia immersed in the branches 
and arranged in two longitudinal rows divided by a central 'super- 
ficial' keel, on which are often prominences. Orifice of Zo88cia small, 
circular, and prominent when preserved." (Carb. Fenestellidae, G. 
W. S., p. 179 Quart. Jour. GeoL Soc, May, 1881. 
1. Fknestella PLEBiA. McCoy, Syn. Carh. Fos., Ireland, p. 29, Fig. 3. 
= It. Jliistrlformis, Fhilli-ps, Geol Yoi-kshire, pi. i., Figs. 11-12. 
= JR. irregularis, „ „ ,, „ „ 21-22. 
= R. undulata, ,, „ „ „ IG-IS. 
Phillips' descriptions of these species are brief and unsatisfactory. 
Of the first, very few particulars are given : R. irreuglaris and 
R. undulata are different portions of the same species, and Mr. 
Shrubsole has done well in selecting the well-described F. jMia, 
McCoy, as the type of this group. In the Derbyshire specimen the 
Zoarium is a flat expansion, the dissepiments are thin, and the fenes- 
trules are oval, with four or five zoBecia on each side, and only five 
f enestrules occupy the space of two lines measured ti-ansversely, four 
in the same space in a longitudinal direction. There is nothing in 
this that would interfere with typical F. j^tlehia, other parts of the 
Zoarium would give different results. I have not the least doubt but 
that this is the typical Retepora and Millepora Jtustriformis of 
Phillips and Martin. Phillips' figure is that of a cast, and the same 
specimens show that the mere casts of the fenestrules would give 
in a drawing, precisely the same result as in Figs. 11 and 12. On 
another part of the Zoarium there is a thin crust of Hemitrypa, 
similar to that referred to in my previous paper (Hurst and Richmond 
Polyzoa^ p. 335, 1881). The specimens of F. plebia from Settle are 
more in accord with the Welsh and Scotch examples of the type : 
the *' fenestrules are equal, rectangular, from two to three times as 
long as wide." 
