DESMEPORA. 
Ill 
Besmepora semicylindrica, Hennig, 1894. Bry. Sver. Krit. ii., Cycl. : Lunds 
L^niv. Arsskr. vol. xxx., Acta Physiogr. No. viii. 
p. 30. 
,, ,, Canu, 1900. Bry. Tours : C.R. Assoc, franc;. Av. Sci. 
1899, p. 40. 
Truncatula ,, Kade, 1852. Los. Yerst. Schanzenb. p. 31. 
,, ,, pars, Boll, 1852. Geogn. Mekl. : Arch. Yer. Naturg. 
Meklenb. vol. vi. p. 63. 
,, ,, d’Orbigny, 1854. Bry. Cret. p. 1054. 
Idmonea dixoniana, Mantell, 1844. Med. Great, vol. i. pp. 284, 287-8, 
figs. 6, 12. 
,, cretacea (now Edw.), Mantell, 1854. i5ic/.,2nded., vol. i. pp. 268, 
271, figs. 6, 12. 
OscuUpora truncata, pars, d’Orbigny, 1850. Prod. Pal. vol. ii. p. 267. 
Truncatula ,, pars, "Winkler, 1864. Mus. Teyl., Cat. Pal. livr. ii. 
p. 207. 
Diagnosis. 
Zoarium of long branches, which dichotomize rarely. The 
obverse surface is flat and the reverse rounded. The branches 
are usually somewhat sinuous and gracefully curved. 
The lateral tufts may end in a sharp point or they may be low 
and flat-topped. The areas between the zooecial tufts are 
occupied by sharp, intersecting ridges separated by pores. 
The average number of apertures in a zooecial tuft is about 
eight, and the tufts are usually a millimetre apart. 
Dimensions. 
Homer’s 
type. 
Lonsdale’s 
specimen. 
B.M. 
D. 503. 
mm. 
mm. 
mm. 
Length of branch 
7 
Zoarium 
25 high X 
40 wide. 
Diameter of branch 
1*75 
2-2-5 
1-25-1-7 
Diameter of peristomal group 
— 
*5 
•2--4 
Length of peristomal group 
— 
•5-1 
•6--8 
Diameter of apertures 
— 
about -1 
•06--08 
Distribution. 
British : 
Upper Chalk : Bromley. 
Middle Chalk — Zone of Micraster cortestudinarmm : Chatham. 
T.ower Chalk — Zone of Holaster planus : Dover. 
Chalk (zone not stated) : Offham Pit, Lewes; near Maidstone ; Beachy Head ; 
Charing. 
