162 



varieties of them at Grignon, was much disposed to place them under 

 the same genus, until he adverted to the circumstance of the spiral 

 turns in these shells being contiguous, whilst in Spirula they are se- 

 parate. 



They in general form one or two spiral turns in a horizontal direction, 

 and then become elongated in a straight line. In some species there is 

 only a little curvature, instead of the spiral turns; and, in others, the 

 whole shell is entirely straight. Some have their spiral turns flattened, 

 others have them cylindrical ; but the chambers in all form some degree 

 of projection externally, which gives the shell the appearance of being 

 divided by transverse ridges. May not the straight species be the Nau- 

 tilus radicula of Montague? Plate XI. Fig. 8 and 9, represent the dif- 

 ferent species particularized by Lamarck ; S. depressa and S. cylindracea, 

 Fig. 10, being supposed to be a variety of S. cylindracea, Fig. 9. 



LXXXIX. Miliola. A transverse, ovato-globose or elongated, mul- 

 tilocular univalve, with transverse chambers, involving the axis alter- 

 nately, and in three directions : the opening small and circular, or oblong, 

 at the base of the last chamber. 



The frequency of these fossils, in the neighbourhood of Paris, is such, 

 that some species of them form the principal part of the masses of stone 

 in some of the quarries. Lamarck describes seven species : and gives 

 figures of live of these species, which are here copied. These figures 

 are considerably magnified, the actual size being about that of a grain 

 of sand, Plate XI. Fig. 11, is Miliolites ringens ; Fig. 12 and 13, are 

 of M. Saxorum ; Fig. 14, 15, and 16, of M. cor anguinum ; Fig. 17, 18, and 

 19, of M. trigonula; and Fig. 20, of M. opposita. The other species men- 

 tioned by him are, M. planulata and M. birostris. 



It is also mentioned by this author, that he possesses recent specimens 

 of these animals, which were taken on focus, near the Island of Corsica. 

 Agreeable to this account of Lamarck's, of these animals having been 

 found in a "recent state, are the discoveries of the late Mr. Boys and of 



