CORALS OF THE LONDON CLAY. 15 
and 7. Nystiana,' to which it is, however, closely allied. The species which it resembles 
most are, however, Zurbinolia Diaonii, T. humilis, and T. Bowerbankii The last of these 
differs from 7. sulcata by its form, which is more elongate and conical, by the thickness 
of the lower part of its primary costs, and by its very slender columella. Zurbcnolia 
Dixonii is easily distinguished by its compressed columella, by the enlargement of its walls 
near the calice, and by the great prominence of its costae. To conclude this brief com- 
parison, we must add, that Zyrbinolia sulcata differs from 7. humilis by its size, by its 
form, which is not near so cylindrical as in the latter, and by the normal number of its 
septa. 
This species is extremely abundant in certain localities of the environs of Paris, such as 
Grignon, Parnes, and Auvert; it is also found in the tertiary strata of Hauteville, in 
Normandy, and in the London Clay at Bracklesham Bay, but it is not common in this last- 
mentioned deposit. We are indebted to Mr. Frederick Edwards and to Mr. F. Dixon for 
the specimens figured in this Monograph. 
2. Tursinonia Dixonir. ‘Tab. III, figs. 1, la, 14, le, ld. 
Tursinoiia Dixonut, Milne Edwards and J. Haime, Monogr. des Turbinolides, Ann. des 
Sc. Nat., 3™° série, vol. ix, p. 238, tab. iv, figs. 2, 2a, 26. 1848.4 
as suLcaTa, Lonsdale, in the MS. work of M. Dixon on the Chalk Formations and 
Tertiary Deposits of Sussex. 
Corallum slightly contracted just above its basis, and rather inflated near the calice. 
Coste very thin, and projecting very much, especially towards the lower part of the wall ; 
those of the third cyclum begining very near the basis, and those of the first and second 
cycla begimming almost at the same height. Intercostal furrows nearly of the same size 
very broad, and very deep; intercostal dimples very distinct, separated by small transverse 
lamine, disposed as usual, in two vertical rows, and prolonged laterally, so as to produce 
the appearance of transverse fluting on the sides of the costa ; about ten of these dimples 
1 We have given this specific name to the Turbinolia described by M. Nyst, and considered by that 
author as being referable to the Turbinolia sulcata (see Coquilles et Polyp. des Ter. tert. de la Belgique, 
p- 629; but not the corresponding figure, which is copied from the work of Goldfuss, and belongs to 
T. sulcata). In order to facilitate the comparison between the British Turbinolia and the species found in 
other countries, we think it may be useful to point out the characteristic features of the 7. Nystiana, which 
were not known to us when we published our Monograph of Turbinolidee. 
Turbinolia Nystiana, nob. (T. sulcata, Nyst, loc. cit.) Corallum elongated, slightly contracted a little 
above its basis, and somewhat inflated near the calice. Coste very slightly prominent, and rather thick ; 
the primary and secondary ones very broad towards the basis; the dimples of the intercostal furrows very 
small, but distinct, and those of one series alternating with those of the other. No rudiments of a fourth 
cyclum of costee. Columella small, and almost cylindrical. Septa rather thick, slightly granulated, and 
forming three complete cycla. Length 34 lines; diameter of the calice 13 line. Fossil from the environs of 
Brussels. (Cabinet of M. Nyst at Louvain.) 
2 See tab. ii, fig. 4. 3 See tab. ii, fig. 3. 
4 In fig. 2@ of this plate, the principal septa are not broad enough towards the calice, and the 
concavity of their inner edge is placed rather too high. 
