32 BRITISH FOSSIL CORALS. 



condition that we cannot give any decided opinion as to their specific identity with the 

 Corals described above. 



Styloccenia emarciata differs from 8. monticularia^ and from S. Taurinensis 1 by the 

 number of the large septa which in the latter species is only six ; it differs much by its 

 general form from 8. Lapeyrousiana? and resembles most 8. Iobato-rotundata, 4 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. Stylocoinia monticularia. Tab. V, figs. 2, 2 a, 2 b. 



Stylopora monticularia, Schweigger, Beob. auf Naturg. reisen, tab. vi, fig. 62, 1819. 



(Correct figure.) 

 Astrea hystrix, Defrance, Diet, des Sc. Nat., vol. xlii, p. 385, 1826*. 

 Cellastrea hystrix, Blainville, Diet, des Sc. Nat., vol. lx, p. 342, 1830 ; Manuel d'Actin., 



p. 377. 

 Astrea hystrix, Michelin, Icon., p. 160, tab. xlv, fig. 1, 1845. 

 Styloccenia monticularia, Milne Edwards and J. Haime, Ann. des Sc. Nat., 3 me serie, 



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. 2 b). The 

 exterior surface of this hollow mass is covered with the calices, 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 striae. The columella is 

 very slender, prominent, free a great way down, cylindrical towards the apex, and slightly 

 compressed at the basis. The septa form only two complete cycla ; the primary ones are 

 much larger than those of the second cyclum, broad, not exsert, granulated laterally, and 

 terminated 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 Stylocoenia emarciata, and 8. Iobato-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. xiii, fig. 2. 



3 Michelin, op. cit., tab. lxx, fig, 3. 4 Michelin, op. cit., tab. xiii, fig. 2. 



