260 
SriROPOEA.. 
Affinities. 
This is a typical member of the Sj^iropora "roup. It differs 
from the type of the geuiis ^ by having more delicate branches and 
more regular arrangement of the peristomes. S. elegam is most 
nearly allied to the annulata form. 
D’Orbigny at first proposed a considerable series of specific 
names for forms which he subsequently included in two species. 
Marsson showed that one of them was a synonym of Goldfuss’ 
C. verticillata^ but kept d’Orbigny’s S. cowmona distinct on account 
of the greater thickness of the branches. Pergens has included 
this ‘ species ’ also in /S', verticillata, a course which I follow. 
The Cricopora verticillata of Michelin appears to be the same 
form as that which d’Orbigny subsef[uently figured as Cricopora 
interrupta, and then merged as a variety or deformity of his 
S. cenomana. IVOrbigny’s suggestion is probably correct. 
The Australian Cainozoic Bryozoan referred to this ‘ species ’ by 
Waters and Macgillivray has a longer free peristome than I have 
seen in any Cretaceous specimen. Macgillivray’s figure shows the 
free peristome as ec^ual in length to the diameter of the internode 
above. The longest peristome of any specimen of S. verticillata 
in the Museum collection (D. 664) is only half that width. 
Macgillivray assigns to S. verticillata a range from the “ Jurassic 
to late Tertiary,” while Waters extends it backward as far as 
the Ordovician. But if any such range be given to the species its 
name must be altered to S. elegans. 
The Cricopora verticillata of von lleuss is a Cainozoic repre- 
sentative of S. macropora^ and not of the true 8. verticillata of 
Goldfuss. 
LIST OF SPECIMENS. 
imiTISH. 
D. 423. A branched fragment with the apertures verticillate above and spiral 
below. Middle Chalk. Chatham. Gamble Coll. Figd. PI. XI. 
Fig. 5. 
D. 3105. A fragment 8 ’5 mm. long, on flint. Upper Chalk. Bromley, Kent. 
Bowerbank Coll. 
D. 664. Three fragments with well-raised peristomes, and one specimen indet. 
(on slide). Middle Chalk. Chatham. Vine CoU. 
1 Spiropora elegans, Lamoiiroux. Expos. Meth. p. 47, pi. Ixxiii. figs. 19-22. 
