432 
ELEMENTS OF GEOLOGY. 
It will be seen that the more ancient corals have what is 
called a quadripartite arrangement of the chief plates or la~ 
mellce —parts of the skeleton which support the organs of 
reproduction. The number of these lamellae in the Palaeo¬ 
zoic type is 4, 8, 16, etc.; while in the ISTeozoic type the num¬ 
ber is 6, 12, 24, or some other multiple of six; and this holds 
good, whether they be simple forms, as in Figs. 474, a, and 
475, a, or aggregate clusters of corallites, as in 474, c. But 
further investigations have shown in this, as in all similar 
grand generalizations in natural history, that there are ex¬ 
ceptions to the rule. Thus in the Lower Greensand Holo- 
cystis elegans (Ed. and H.) and other forms have the Palaeo¬ 
zoic type, and Dr. Duncan has shown to what extent the 
Neozoic forms penetrate downward into the Carboniferous 
and Devonian rocks. 
From a great number of lamelliferous corals met with in 
the Mountain Limestone, two species (Figs. 476, 477) have 
Lithostrotion basaltiforme, Phil. sp. 
(Lithostrotion striatum, Fleming; 
Astrcea basaltiformis, Coiiyb. and 
Phill.). England, Ireland, Rus¬ 
sia, Iowa, and westward of the 
Mississippi, United States. (D. D. 
Owen.) 
Fig. 4TT. 
Lonsdaleia jloriformis, Martin, sp., M. 
Edwards. {Lithostrotion jioriforme, 
Fleming. Strombodes.) 
a. Young specimen, with buds or cor¬ 
allites'on the disk, illustrating cali- 
cular gemmation, b. Part of a full- 
grown compound mass. Bristol, 
etc.; Russia. 
been selected, as having a very wide range, extending from 
the eastern borders of Russia to the British Isles, and being 
found almost everywhere in each country. These fossils, to¬ 
gether with numerous species of Zaphrentis^ Amplexus^ Cy- 
athophyllum^ Clisiophyllum^ Syringopora^ and Michelinia^' 
form a group of rugose corals widely different from any that 
followed them. 
* For figures of these corals, see Palaeontographical Society’s Monographs, 
1852. 
