264 
SPIROrORA. 
Affinities. 
This Spiropora differs from S. vertkillata by the eloser proximity 
of the transverse series of apertures. The synonymy is com- 
plicated, and it is improbable that any two hryozoologists would 
adopt the same limits for the species. At first I adopted Pergens’ 
arrangement of this group ; hut that appears to me to involve two 
inconsistencies and to he unworkable. Pergens accepts Spiropora, 
but includes Laferotuhigera cenomana as a variety of JEntalophora 
ramosksima, characterized by the vertieillate arrangement of tlie 
apertures. Hence the character on which Spiropora is accepted 
as a genus is elsewhere regarded as of less than specific value, 
Pergens, moreover, separates d’Orbigny’s species macropora from 
the Jlexuosa-amiulato-spiralis series, mainly on account of the size 
of the zooecia and apertures ; but he includes in macropora, as 
a variety, the form micropora, in which the apertures and zooecia 
are as small as in the other series. 
The dimensions of the zooecia in this species seem to vary con- 
siderably. Thus, among d’Orbigny’s series of species his annulato- 
spiralis (pi. 754, figs. 8-11) appears to be a young branch of the 
same form as macropora (pi. 754, figs. 5-7); the fexmsa (pi. 754, 
figs. 2-4) has more crowded, smaller zomcia, and appears to be 
intermediate between the macropora and w/‘6rr>/orrt(pl.754,figs.l2-14) 
forms; the cenomana form (pi. 618, figs. 11-15) agrees with flexuosa\ 
the annulata (pi. 762, figs. 13-15), as Pergens has shown, is a hollow 
specimen of the same form, though agreeing with the micropora 
rather than with macropora, in which Pergens placed it. The Upper 
Greensand iorm jesmii is a representative of the macropora scries. 
I have in vain endeavoured to separate this group of specimens 
into two species by the size of the apertures, dividing those with 
apertures of about *06 mm. — according to Pergens’ measurement for 
\ns, pulcliella series — from those in which it is from *12 to *15 mm. 
But Pergens himself remarks that “ the difference of this species 
\_Spiropora macropora^ from Spiropora {Entaloplioroi) pulchella is not 
strongly marked, and j>erhaps it is composed only of aged colonies.” 
The name macropora is inappropriate for the species, as it includes 
the micropora variety ; but the specific name cenomana is no better, 
as the species is mainly Senonian, and as that name has been 
very loosely used, and is liable to be superseded on the ground 
that it had been previously used by d’Orbigny for a Cricopora 
which must be included in Spiropora (p. 258). 
