CORALS OF THE LONDON CLAY. 23 



Columella fasciculate, with very slender elements. Septa forming six complete cycla, 

 closely set, very thin and broad ; those of the first three cycla nearly equal. Pali rather 

 large, and thin, scarcely thicker than the septa, and presenting laterally spiniform granu- 

 lations ; those corresponding to the penultimate cyclum of septa being the most developed, 

 the others nearly equal. 



This Coral soon acquires all its septa and its final diameter, but continues growing up, 

 so that it becomes sometimes very tall, without expanding proportionally ; we have seen 

 specimens three or four inches high, or even still longer. It has been found in the lower 

 tertiary deposits of several localities in the south of France and the north of Italy. 



3. Genus Paracyathtjs (p. xiv). 



1. Paracyathus crassus. Tab. IV, figs. 1, la, 1 b, \c. 



Corallum subturbinate, short, fixed by a very broad basis, slightly contracted just 

 above the lower end, and rather inflated at the upper part. Costa well marked from top 

 to bottom, closely set, nearly equal in breadth, but alternately more or less prominent, 

 especially near the calice, and covered with very delicate granulations. Calice nearly 

 circular when young, but becoming soon more or less oval; fossula deep. Columella 

 concave, papillose, thick, and not distinctly separated from the inner lobes of the pali. 

 Septa forming four complete cycla, and an incomplete rudimentary fifth cyclum, in one half 

 of the systems corresponding to the long axis of the calice ; closely set, straight, slightly 

 exsert, thin towards the centre of the visceral chamber, rather thick externally, granulated 

 laterally, and unequally developed according to relative age. Pali corresponding to the 

 septa of the first three cycla, thick, tall, strongly granulated, and denticulated along the 

 inner edge, which is rather oblique ; those corresponding to the tertiary septa larger than 

 the others, and those that correspond to the primary septa being the smallest of all. 

 Height, five or six lines ; long axis of the calice, four lines ; short axis, three lines ; depth 

 of the fossula, three lines. 



This Paracyathus is easily distinguished from the other species of the same genus by 

 the number of the septa, which in P. procumbens} P. Stokesii, 2 and P. liesnoyersii, form an 

 additional cyclum ; by the size of the pali, which are much thicker than in P. caryophyllus , 

 and P. brevis? and by the lobulate edge of these same organs, and the oval form of the 

 calice, from P. aquilamellosus, P. Pedemontanus? and P. Turonensis. 



Paracyathus crassus has as yet been found only in the London Clay of Bracklesham 

 Bay, and has been communicated to us by Mr. Dixon and Mr. Frederick Edwards. 



1 Milne Edwards and J. Haime, Monogr. of Turbinolidse, in Ann. Sc. Nat., 3d ser., vol. ix, pi. x, fig. 6. 



2 Idem, loc. cit., pi. x, fig. 7. 3 See tab. iv, fig. 2. * See tab. iv, fig. 3. 

 6 Caryophylha pedemontana, Micbelin, Icon., pi. ix, fig. 16. 



