CORALS OF THE LONDON CLAY. 17 



cyclum of costae appearing near the calice, and consisting in very short, prominent, thin 

 lines, most developed between the primary and the tertiary septa. Intercostal furrows 

 rather narrow, but presenting very clearly a double row of small dimples. Calicular 

 fosmla not deep. Columella cylindrical, prominent, and very slender in proportion to the 

 size of the calice. Septa very thin, exsert, rather unequal, and forming six regularly- 

 developed tertiary systems (fig. 3 5). No traces of a fourth cyclum of septa corresponding 

 to the rudimentary costae of the fourth cyclum. The tertiary septa joining the primary 

 ones very near the columella. The lateral surfaces of all the septa presenting delicate 

 granulations. Height two lines ; diameter of the calice one line and a third. 



This species bears great resemblance to Turbinolia Fredericiana ; it differs from it by 

 the rudimentary state of the fourth cyclum of costae, and by its slender, round columella. 

 The existence of well-formed intercostal dimples distinguishes it from T. minor, T. costata, 

 T. Prestwichii, and T. jirma ; the costae are much less prominent than in T. sulcata, 

 and T. Dixonii, from which this Coral may also be distinguished by its form ; the costae 

 are thinner than in T. pharetra and T. Bixonii, and the complete development of its six 

 systems of septa does not admit of its being confounded with T. humilis. 



We have seen but one specimen of this species ; it was found at Barton, and belongs 

 to the collection of the fossils of the London Clay formed by Mr. Frederick Edwards. We 

 have dedicated it to our friend Mr. J. S. Bowerbank, whose active researches have much 

 contributed to the extension of our knowledge relative to this portion of British 

 palaeontology. 



4. Turbinolia Fredericiana. Tab. Ill, figs. 2, 2 a, 2 b. 



Corallum of a regular conical form, not much elongated, and rather broad towards the 

 calice. Costa numerous, forming four cycla, closely set, unequal, and projecting very 

 little ; the secondary ones beginning a little above those of the first cyclum, but very near 

 the basis of the corallum, and being, as well as the former, much thicker near their lower 

 end than higher up, where they become very delicate (fig. 2 a). The tertiary costae begin 

 also at a short distance from the basis, but those of the fourth cyclum appear only in the 

 upper half of the corallum ; they are also rather thinner than the others. The intercostal 

 furrows very narrow, and not very deep ; the mural dimples not very apparent, small, 

 closely set, and forming towards the calice, if not from top to bottom, only a single series 

 in each intercostal furrow. Calicular fossula very narrow and shallow. Columella thick, 

 compressed, granulated, rising higher than the septa, and presenting well-marked pro- 

 longations of the principal septa. Three cycla of septa, and no vestiges of a fourth 

 cyclum corresponding to the quaternary costae (fig. 2<5). The septa are much like those 

 of the two preceding species, but they are a little thicker, and not so exsert ; the primary 

 ones are, as usual, narrower than the secondary ones, and these reach higher up along the 

 columella; the tertiary septa are small, and join the primary ones, but appear to be 



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