182 
CRT SIN A. 
zoarium is thus easily distinguished fi’om R. ohliqua, hut 
fragments of the young zoaria of the two species are not easily 
separated. The zoarium of R. papyracea is tufted rather than 
reticular; hut some zoaiia, such as that represented by PL IX. 
Pig. 3, tend to gi’ow into rather nodular zoaria, like the 
mseandriform zoaiia of Diastopora michelini (Blv.).^ 
The occuiTence of the scattered apeiiures on the reverse edge 
presents an approximation to the rudimentary character of that 
edge in Reticrisina clidicha (Gldf,). 
D. 3965. 
LIST OF SPECIMEXS. 
Two fragments of zoaria. Middle Chalk. Chatham. Gamble Coll. 
Figd. PI. IX. Figs. la-c. 
D. 385. 
Four fragments of young zoaria of the var. complanata. Middle 
Chalk. Chatham. Gamble Coll. The reverse edge of one 
specimen, showing the irregular series of zooacia, is figured ou 
PI. IX. Fig. 2. 
B. 70. A young zoarium. Middle Chalk (? zone of Holaster planus'' 
D. 3046. 
Freshwater, I. of AVight. J. S. Gardner Coll. Figd. PL IX. 
Fig. 3. 
Parts of a large zoarium in flint. Upper Chalk. Bromley. 
J. Simmons Coll. 
D. 2752. 
A fragment of young zoarium on slide, the var. complanata. Middle 
Chalk. Chatham. ATne Coll. 
D. 674. 
Two fragments on slide. Middle Chalk. Chatham. ATne Coll , 
Xo. 28. Identified by A^ine as E. papyracea. 
3. Crisina (Reticrisina) disticha (Goldfuss), 1827. 
Syxoxtait. 
Eetepora disticha^ pars, Goldfuss, 1827. Petref. Germ. vol. i. p. 29, pi. ix. 
? J 
figs. 15c, d, and Pfigs. 15i, k\ not figs. 15a, b, e-h. 
,, pars, Alorren, 1829. Descrip. Cor. foss: Beige : Ann. Acc. 
Groning. 1828, p. 36. 
,, pars, Kloden, 1834. ATrst. Brandenb. p. 264. 
,, Milne Edwards, 1836. In Lamarck, Hist. nat. Anim. sans 
A^ert., 2nd ed., vol. ii. p. 281. 
,, pars, von Hagenow, 1839. Mon. Eiig. : Xeu. Jahrb. 1839, 
p. 281. 
Idmonea 
,, pars, de Blainville, 1830. Zooph. : Diet. Sci. nat. vol. lx. 
p. 386. 
1 Cat. Jur. Bry. p. 124. 
