u 
CEETA.CEOUS COEALS OE AETHOZOA 
5. TnAMNASTREA INDTJTA, StoliczJca. PI. IX, Pig. G, and PL X, Eig. 1. 
Thamnast. corallum obverse conoideum, hasi angustata aut latiuscula ajjixiim, 
epithecd crassa, concentrice distanter rugosa, in rugis atque prope marginem supe- 
riorem costis granuUfei'is notata, indiitum, supra leviter convexhisciilnm ; calycibus 
duobiis, vel plnribus, paulo majorihiis serie unica niinorum plus minusve con- 
Jliientium prope peripheriani sita circumdaUs, theca costo-murali satis distincta 
seporatls, paulisper concavmscuUs, majorihiis rotundate polygonis, 6 ad 7 mm. latis, 
cum septis in quatuor cyclis dispiositis, cyclo quarto imperfecto, alteris minorihus 
septis in duobus aut tribus cyclis dispositis, cyclo tertio imperfecto ; septis omninis 
lateraliter crasse gramilatis. 
This species is in some respects intermediate between JDimorphastrea and 
Thamnastrea, as there are some calyces enlarged in the centre, regularly surrounded 
by a series of smaller ones ; the central ones have also a larger number of septa 
than the row of smaller ones, but on account of the greater number of central 
calyces, the species is, I think, more correctly referable to Thamnastrea than 
to Dimorphastrea. Whether this distribution is a merely accidental occuiTence, 
cannot be for the present ascertained, because only two specimens exist in the 
collection, and these are not very perfectly preserved, except on the sections. 
The corallum was eA’idently sessile, with a tolerably broad base, and is covered with 
a well developed, thick epitheca, marked at some distances with concentric rugosities, 
on which, as well as near the upper edge, rather coarsely granular, equal ribs are to 
be observed. The septo-costal murail is well developed. The columella is distinctly 
papillose or spongiosc in all calyces. 
Locality. — Odium, in a brown earthy limestone ; very rare. 
Formation. — Ootatoor group. 
XX. Genus. — DIMOEPIIASTEEA, d'Orbigny, 1850. 
Corallum of moderate size, compound, externally covered with an epitheca ; 
calyces confluent, connected by a rudimentary costo-mural theca ; the median one 
is the largest, the others arranged in more or less regular concentric series ; costae 
generally elongated and, like the septa, serrated, and laterally granular ; columella 
spongiose or papillose. 
The genus differs from the previous one simply by the arrangement of the 
calyces, of whicli a single central one is the largest. 
Species of Dimorphastrea are at present only known from cretaceous and ter- 
tiary deposits ; they are, however, much less numerous than the Thamnastrece. 
( 170 ) 
