32 BRITISH FOSSIL CORALS. 
condition that we cannot give any decided opinion as to their specific identity with the 
Corals described above. 
Stylocenia emarciata differs from S. monticularia,’ and from S. Taurinensis? by the 
number of the large septa which in the latter species is only six ; it differs much by its 
general form from S. Lapeyrousiana,’ and resembles most S. obato-rotundata,* from which 
it may be distinguished by a greater development of the mural tubercles, the tenuity of 
the septa, and the general form of the mass. 
2. Stytoc@nia MonticuuaRtia. ‘Tab. V, figs. 2, 2a, 26. 
STYLOPORA MONTICULARIA, Schweigger, Beob. auf Naturg. reisen, tab. vi, fig. 62, 1819. 
(Correct figure.) 
ASTREA HysTRIX, Defrance, Dict. des Sc. Nat., vol. xlii, p. 385, 1826. 
CELLASTREA HystTRIX, Blainville, Dict. des Sc. Nat., vol. lx, p. 342, 1830; Manuel d’Actin., 
p. 377. 
As?REA HysTRIX, Michelin, Icon., p. 160, tab. xlv, fig. 1, 1845. 
SvYLoc@NIA MONTICULARIA, Milne Edwards and J. Haime, Ann. des Se. Nat., 3™ série, 
vol. x, p. 294, 1848. 
Corallum composite, elongated, and nearly cylindrical when young, but becoming, by 
the progress of growth, oval, sub-globose, and free, (fig. 2) ; with an empty central cavity, 
the parietes of which are coated with a thin epitheca, wrinkled circularly (fig. 24). The 
exterior surface of this hollow mass is covered with the ca/ices, the borders of which vary in 
form according to the age of the compound Coral; when the colony of polypi is young, the 
margins of the calices are circular, prominent, and separated from each other by a striated 
surface ; but in older groups, they become polygonal and united, so as to form a single 
thin ridge common to the two neighbouring corallites. The mamilliform processes that 
rise at the angles of the calices are stout, conical, broad at the basis, and covered with 
numerous prominent, sub-lamellar, finely-denticulated, vertical striz. The columella is 
very slender, prominent, free a great way down, cylindrical towards the apex, and slightly 
compressed at the basis. The sey/a form only two complete cycla ; the primary ones are 
much larger than those of the second cyclum, broad, not exsert, granulated laterally, and 
termimated by an undivided convex edge. Sometimes the striae of the mural processes are 
continued down along the parietes of the visceral chamber, and assume the appearance of 
rudimentary septa. Diameter of the calice, two thirds of a line ; height of the mural 
processes, half a line. 
This species differs from Stylocenia emarciata, and S. lobato-rotundata, by the regular 
and equal development of the six systems of septa, whereas, in the latter, two of these 
1 See tab. iv, fig. 2. 2 Michelin, Icon., tab. xii, fig. 2. 
° Michelin, op. cit., tab. lxx, fig. 3. * Michelin, op. cit., tab. xii, fig. 2. 
