162 
cursiNA. 
Figures. 
PL YIII. Fig. 5. Part of a h*pical branch, x 12 dia. Middle 
Chalk : Chatham. Gamble Coll. * D. 3979. 
PI. YIII. Fig. 6. Branch of another zoarium, seen in Fig. 6a 
from the obverse and in Fig. from the side; x 12 dia. In the 
lower part of this branch the apertures are sometimes bisenal. 
Upper Chalk : Gravesend. Yine Coll. D. 963. 
Affinities. 
This ‘ species ’ is the simplest of the Crisi?us, and Y'aters has 
suggested that it may be a Crisia. The Australian specimens, 
however, referred to the species by Waters seem to me specifically 
distinct. 
The branchlets often retain the unisenal apertures for lengths of 
several millimetres ; a specimen on slide D. 3979 is 6 mm. long : 
this shows that the zooecia are not immature foims of multiserial 
‘ species,’ though the tips of the branches in some other Idmonea 
are uniserial. 
Pergens remarked that the only reason why he did not unite 
the species desciibed by him as /. f rancor um with 2. unipora is, that 
the diameter of the apertures are respectively *06 and -09 mm. 
LIST OF SPECIMENS. 
D. 3979. Three fragments (on slide). Middle Chalk. Chatham. Gamble Coll. 
Figd. PL YIII. Fig. 5. 
D. 963. Two fragments (on slide). Upper Chalk. Gravesend. T. R. Jones 
Coll Purchased in Yine Coll. Figd. PI. YIII. Fig. 6. 
D. 2646. Four small fragments (on slide). Upper Chalk. Gravesend. 
T. R. Jones Coll. Purchased in Yine Coll. 
D. 445. Four fragments (on slide). Middle Chalk. Chatham. Gamble Coll. 
2. Crisina cenomana, d’Orbigny, 1850. 
Synonymy. 
Crisina cenomana, d’Orhigny, 1850. Prod. Pal. vol. ii. p. 175. 
,, ,, d’Orhigny, 1851. Bry. Cret. pi. 614, figs. 1-5. 
Idmonea ,, d’Orhigny, 1853. Ibid. p. 732. 
,, ,, Pergens, 1890. Rertsion, p. 344, pi. xii. figs. 3, 13. 
,, disticha {non Goldf.), Michelin, 1845. Icon. Zooph. p. 204, pi. lii. 
fig. 18. 
,, calypso, d’Orhigny, 1853. Bry. Cret. p. 733, pi. 747, figs. 10-14. 
