CARBONIFEROUS FENESTELLID ®. 281 
details been removed until it is plainly the Fenestella nodulosa, Phill. 
The connexion between the two forms can scarcely be more closely 
established, every link in the chain is complete. 
It is quite true that the early workers among the Polyzoa failed 
to see the true generic form of Fenestella. The circumstance that 
we have it now clearly established in these ornate forms of the 
Fenestellide scarcely warrants the creation of a new genus for their 
reception. It is admitted that the group has hitherto been only 
imperfectly described, and that the genus needs revision. This I 
hope to accomplish shortly. When this is done, the retention of 
Actinostoma will be unnecessary. I see no objection to the retention 
of Phillips’s name for this species, Fenestella nodulosa, even with the 
additional details to be given to it. 
FENESTELLA MEMBRANACEA, Phill. 
Fenestella tenuifila, Phill., Geol. Yorks. pl. 1. figs. 23, 24, 25. 
EF, hemispherica, M‘Coy, Syn. Carb. Foss. Irel. pl. 29. fig. 4. 
F, flabellata, Phill., Geol. Yorks. pl. 1. figs. 7-10. 
Hemitrypa hibermca, M‘Coy, Syn. Carb. Foss. Ireland, p. 205, 
pl. 29. fig. 7. 
The above are the most minute and delicate of the British forms. 
In size and specific characters they are all, within reasonable limits, 
identical. 
Fenestella membranacea, Phill., differs in shape from all the other 
Carboniferous varieties. The commencement of its growth was a 
hollow cone with anchoring rootlets ; the cone rapidly widened and 
expanded outwards, forming folded and lobed fronds around the 
original cone. The cone is Fenestella membranacea, Phill.; the 
upper and expanded part of the polyzoarium is known as Fenestella 
flabellata, Phill., and Fenestella tenwfila, Phill. Sometimes the 
conical base commenced its outward extension somewhat earlier, 
causing it to assume a somewhat globose shape; in this state it is 
the Fenestella hemispherica, M‘Coy. It is only right that I should 
state that W. H. Baily regards Fenestella membranacea, Phill., as 
identical with /. hemispherica, M‘Coy *. 
Now as to these synonyms: looking.to the complete agreement 
which exists as to pore-cells, interstices, and dissepiments between 
Fenestella membranacea, F. tenuifila, and F’. flabellata there need be 
no doubt or hesitation in allowing the ‘spreading corallum” in 
Prof. M‘Coy’s description of Fenestella flabellata to resume its right 
place on the “elongate conical polyzoarium ” of Phillips’s Fenestella 
membranacea. Inso doing we not only make it a “ thing of beauty,” 
but, what is still more important, restore it to its true life-form. 
I will now allude to the genus Hemitrypa, M‘Coy. As such 
its claims are not now for the first time called in question. It is 
described as having “ an internal network covered with an external 
sheath,”’ while of Hemitrypa hibernicat we are told that “the in- 
* Baily’s Paleozoic Foss. p. 107. 
+ M‘Coy’s Syn. Carb. Foss. Ireland, p. 205. 
