CORALS FROM THE GREAT OOLITE. 115 
Tsastrea limitata differs from I. helianthoides,' I. explanata, I. Munsterana,s I. crassa, 
I. lamellosissima, I. Bernardana,’ T. tenuistriata,' I. ornata,® and J. serialis,? by the small 
size of its calices, and by its septa beg more numerous. It differs from L. polygonalis, 
I. oblonga,” and I. Michelini,” by its walls being very thin, although well formed ; from 
I. explanulata® by the concavity of its calices, and from 7. Richardsoni* by the tenuity of 
its septa. It bears strong resemblance to 7. Guettardana,” but in the latter the calices are 
rather deeper, and the septa more delicate, less numerous, and developed in a more equal 
manner. Having lately been enabled to examine the fossils mentioned by M. D’Orbigny 
under the names of Pronastrea alimena and P. Luciensis,'® 
we have no longer any doubt 
as to their being specifically identical with the coral here described. We are also inclined 
to think that the two fossils for which the same author has established the genus Dendras- 
trea” are only subdendroid varieties of Zsastrea Himitata ; but they are too ill preserved for 
us to be able to decide the question. 
3. IsASTREA EXPLANULATA. ‘Tab. XXIV, figs. 3, 3a. 
ASTREA EXPLANULATA, M‘Coy, Ann. of Nat. Hist., s. 2, vol. ii, p. 400, 1848. 
Corallum massive, terminated by an almost flat surface. Calices shallow, not very 
unequal, polygonal. Walls rudimentary, but the corallites distinct, even when deprived of 
a mural investment, and the costal edge of their septa alternating in general with those of 
the adjoining corallite. Col/wmel/a rudimentary. Septa thin, closely set, straight or slightly 
bent, striated laterally, delicately and regularly denticulated along their upper edge, and 
very unequal in size. In general three complete cycla, and a few septa belonging to a 
fourth cyclum appearing in a very irregular manner ; sometimes one half of certain systems 
being more developed than the other ; sometimes the septa of the fourth order are formed 
without beg accompanied by those of the fifth, which equally enter into the composition 
1 Astrea helianthoides, Goldfuss, Petref. Germ., pl. xxii, fig. 4a. 
27 Tabs xxiv.) t1est.3, oa. 
8 Prionastrea Munsteriana, Milne Edwards and J. Haime, Ann. Se. Nat., t. xii, p. 136. 
4 Agaricia crassa, Goldfuss, Petref. t. xii, fig. 13. 
5 Astrea lamellosissima, Michelin, Icon., pl. vi, fig. 1. 
6 Prionastrea Bernardina; D’Orbigny, Prodr., t. i, p. 293. 
7 Tab. xxx, fig. 1. 
8 Prionastrea ornata, D’Orbigny, Prodr., t. i, p. 293. 
9 Tab. xxiv, fig. 2. 
10 Astrea polygonalis, Michelin, Icon., pl. iii, fig. 1. 
Ml Tab. xii, fig. 1. 
2 Montastrea Michelini, De Blainville, Dict. Sc. Nat., t. lx, p. 339. 
3 Tab. xviii, fig. 1. 14. Tab. xxix, fig. 1. 
15 Astrea formosissima, Michelin, Icon., pl. vi, fig. 24. (Non Sowerby.) 
LS Op cits; vOlea, poze: 
 Dendrastrea Langrunensis, D’Orbigny, and D. dissimilis, D’Orb., Prodr., vol. i, p. 322. 
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