380 
PETALOPOEA. 
maculae, a fact which seems to prove that the pohjpora form is only 
a variety. Novak’s figure of his P. seriata {op. c%i. pi. ix. fig. 22) 
shows biserial and multiscrial maculae in the same specimen. 
The var. tenera, Eeuss, is a vaiiety with thin branches and 
multiserial maculae. The var. dumonti, Hag., has distant and 
irregularly scattered apertures, with the longitudinal nbs eitlier 
inconspicuous or absent ; von Eeuss, however, has included in 
dumonti a different form with well-developed vertical ribs. The 
true dumonti of von Hagenow is probably a thick basal fragment 
of P. costata. 
The Cenomanian forms of this species have more sinuous ribs and 
are more frequently polyporous than the Senonian ; the specimens 
available are too fragmentary for the definite detennination as to 
whether the Cenomanian specimens may be specifically separated. 
This can only be settled by comparison of equivalent parts in 
•a considerable series of specimens. 
LIST OF SEECDIEXS. 
British. 
A group of many branches. Chalk. Sussex. Dixon Coll. Figcl. 
by Lonsdale as Pctalopora pulcheUa (Rom.), in Dixon, Geol. Suss, 
pi. xviii. A, fig. 7. 
A distal end of a branch. Chalk. Sussex. Dixon Coll. Figd. 
Lonsdale, op. cit. pi. xviii. a, fig. 7a. 
Middle portion of a branch. Chalk. Sussex. Dixon Coll. Figd. 
Lonsdale, op. cit. pi. xviii. a, fig. 7h. 
Basal portion of a branch, most of which is in the stage polypora ; 
but biporous zooecia also occur. Chalk. Sussex. Dixon Coll. 
Figd. Lonsdale, op. cit. pi. xviii. a, fig. 7c. 
Two branches shoi\ing longitudinal section. Chalk. Sussex. 
Dixon Coll. Figd. Lonsdale, op. cit. pi. xviii. a, fig. 7d. 
A branch showing transverse section. Chalk. Sussex. Dixon Coll. 
Figd. Lonsdale, op. cit. pi. xviii. a, fig. 7e. 
A longitudinal section of part of base of a stem (on slide). Chalk. 
Dover. Bowerbank Coll. Figd. PI. XII. Fig. 8. 
Base of a young zoarium (on slide). Middle Chalk. Chatham. 
Gamble Coll. Figd. PI. XII. Fig. 9. 
A stem of var. appendiculata, with well-raised peristomes (on slide). 
Middle Chalk. Chatham. Vine Coll. Figd. PI. XII. Fig. 10. 
A block of chalk with many branches, some 40 mm. long. Some 
branches of var. Chalk. Offham Pit, Lewes. Capron Coll. 
A block of chalk with several branches of the normal form of the 
worn, eroded pidchella (Orb., non Rom. ncc Lonsd.). Chalk. 
Dover. Bowerbank Coll. 
60,253. 
B. 4480. 
B. 4481. 
B. 4482. 
B. 4483. 
B. 4484. 
D. 7062. 
D. 4514. 
D. 713. 
60,610. 
D. 3085. 
