PEOBOSCDfA. 
31 
PL III. Pig. 4. Part of a zoarium of Tar. toucan^ x 8 dia. 
Middle Chalk : Chatham. Gamble CoU. D. 3813. 
Affen'iiies. 
The main characters of this species are its narrow, irregular 
width, the repeated bifurcation of its branches, its long, narrow 
zooecia, and its irregularly arranged apertures. In some specimens, 
as in von Peuss’s type and Pocta’s Stomatopora disjecta, the zoarium 
is nodulose and subclavate. 
The species is represented by three main varieties : the typical 
Cenomanian form, in which the zoarium is nodulose; the var. 
ziczac, from the Xeocomian, which I only know from the 
fragment figured by d’Orbigny ; and the common Senonian var. 
toucasi, in which the zoarium is usually reticular, and formed of 
bands which vary irregularly in width. Of the three figures 
given by von Peuss of the typical Bohemian form, two are 
insufficiently magnified to show more than the zoarial characters. 
Among the nearest Cretaceous allies of P. fasciculata is 
P. angmtata (Orb.), in which the zoarium is more narrow and 
regular, and the zooecia finer. It is also near to P. ramosa (Edw.), 
in which the branches become wider, expand more regularly, 
and anastomose less frequently. P. sarthacensis (Perg.) and 
P. cornucopia (Orb.) have more crowded zooecia; audit differs 
from P. radiolitorum (Orb.), which parts of the zooecia sometimes 
simulate, by the greater irregularity in distribution of the 
apertures. 
In the Cat. Jur. Bry., p. 63, it was suggested that P. toucasi 
(Orb.) should include the D. ramosa, Mich. ; but after more careful 
examination of the considerable series of specimens of the toucasi 
form in the collection, this proposal seems doubtful. The 
D. ramosa of Michehn, though not weU figured, appears to have 
the zooecia more crowded than in P. toucasi, one of d’Orbigny’s 
types of which has been refigured by Pergens. 
LIST OP SPECIMENS. 
D. 466. A zoarium of var. toucasi on fragment of Echinocorys scutatus. 
Middle Chalk. Chatham. Gamble CoU. Figd. PL III. Fig. 2. 
D. 2669. A zoarium of var. toucasi on a fragment of Inoceramics, sp. Middle 
Chalk. Chatham. Gamble CoU. Figd. PL III. Fig. 3. 
D. 3813. A zoarium of rar. toucasi on a fragment of Echinocorys scutatus. 
Middle Chalk. Chatham. Gamble CoU. Figd. PI. III. Fig. 4. 
