MR J. W. GREGORY ON THE MALTESE FOSSIL ECHINOIDEA. 633 



of Austria,* no attempt seems to have been made to apply this classification to the six 

 divisions of the Miocene adopted by M. LocARDt in Corsica. The Maltese beds seem, in 

 fact, to have been on the border line between two areas, in which different sequences of 

 conditions have necessitated two different classifications of the deposits of the middle part 

 of the Cainozoic era. Hence it may be of interest to see how far the Maltese beds can 

 be correlated with those of the two halves of the Mediterranean region, and see what 

 light the Echinoidea throw on the physical condition of the period. 



The precise correlation of beds in islands with those of other areas is rarely entirely 

 free from some doubt, as the final appeal to stratigraphy cannot be made. But in the 

 case of the Maltese beds there is an additional source of uncertainty, as the comparison 

 frequently has to be made between deposits laid down under very different conditions ; 

 the slight variations produced by age may be completely overshadowed by differences due 

 to altered circumstances, and hence the evidence of palaeontology must be accepted with 

 considerable caution. Thus in Malta the calcareous marls, with fish teeth, &c, occur near 

 the base of the series, and the great Clypeaster beds above ; but in Corsica the succession 

 is reversed. As an area subdivided, its fauna must have withdrawn to shallower regions, 

 whence, on its re-elevation into more favourable zones, they returned to oust the deeper 

 forms that had temporarily supplanted them. Hence the area in question affords illustra- 

 tions of a series of " colonies," though their migrations must have been limited to a much 

 shorter period of time than in the cases, now discredited, for which this theory was 

 originally proposed. 



Before any correlation of the Maltese subdivisions can be attempted with much chance 

 of success, their faunas must be studied with greater care than has apparently been 

 devoted to any of the invertebrates except the Foraminifera and the Echinoidea. As the 

 latter are good zonal fossils, the evidence they afford may be more reliable than that of 

 other groups, at least until far more care has been bestowed on the mollusca than has as 

 yet been done. The Echinoidea, moreover, now offer the additional advantage that their 

 distribution in the Maltese series is known with greater certainty than previously, 

 owing; to the care with which Mr J. H. Cooke has collected these fossils. As in the list 

 compiled by Dr Wright| specimens from Sicily, and probably Egypt, have been included, 

 and errors both of specific identification and of geological horizons seem to have 

 occurred, it has not been accepted as evidence in the compilation of the table of dis- 

 tribution. 



The following table gives the succession of the Maltese beds. It has been kindly 

 compiled for this paper by Mr Cooke. The names are those proposed by Dr Murray, to 

 whose Memoir reference is made for further details, and especially the microscopic struc- 

 ture of the rocks. 



* Sitz. k. Ak. Wiss. Wien, lxx., Abth. i., 1874, pp. 92-105. 



t A. Locard, "Description de la Faune des Terrains tertiares raoyens et superieurs de la Corse," A nn. Soc. Agric. 

 Lyons (4), ix., 1877, pp. 345-360. 



J Quart. Journ. Geol. Soc, 1864, vol. xx. p. 490. 



VOL. XXXVI. PART III. (NO. 22). 5 C 



