86 MK. S. S. BUCK MAX OK [vol. lxxvi r 



The reason for inferring that there are faunas of two dates 

 in the nodular band is the difference in the geographical dis- 

 tribution of those faunas on the Continent ; but it may remain 

 only a working hypothesis for the present, to prove or disprove 

 which further evidence should be collected. 



III. Additional Enquiries. 

 (a) The Hieiiatz and Spezia Faunas. 



The faunas of these areas have been regarded as ' misch- 

 faunas ' and dwarf faunas. As they come considerably under 

 review in connexion with the faunas of the Gloucestershire 

 deposits, it seems appropriate to enquire further concerning them, 

 especially in order to see whether it is in regard to the preserved 

 strata, or in regard to the preserved fauna, or in regard to both, 

 that they are exceptional. 



The strata of Hierlatz and Spezia give the impression of being 

 what may be called highly-condensed deposits, after the pattern 

 of the Junction Bed of the Dorset Coast, which in about 2 feet 

 represents, with many lacunae, what is found distributed through 

 hundreds of feet of strata elsewhere ; and it gives, at first sight, 

 the appearance of being one bed — with a ' mischfauna '. The 

 Hierlatz and Spezia deposits are, perhaps, a still more exaggerated 

 instance, complicated possibly also by much redeposition of 

 specimens. A technical term for such deposits seems to be 

 required — deposits in which condensation, whether produced by 

 paucity of sedimentation, or by penecontemporaneous erosion, or 

 by both combined, has produced the false appearance of con- 

 temporaneity. 



At Wellow near Radstock (Somerset) there occurs, as has been 

 already recorded, 1 a bed of ironshot rock, a hand-specimen of 

 which yielded Uildoceras bifrons and Acanthotliyris spinosa — 

 the names being used in a wide sense : that is, a species of Whitbian 

 (7 [b]) and a species of Vesulian (garantiana). Between these 

 two ironshot deposits, which show but little difference from one 

 another, are to be found, within the radius of a few square miles, 

 some hundreds of feet of strata dejjosited during three Ages and 

 some 26 hemeraa. The gradual disappearance of the intermediate 

 strata b} r erosion can be traced from place to place ; so that, when 

 the climax is reached at Wellow, and the two ironshots coalesce 

 into one block, the phenomenon is so much in accordance with 

 anticipation that it does not excite the astonishment which is it s 

 due. But, let us suppose such coalescence to occur over a fairly - 

 wide extent of country ; and let us imagine that all the other 

 strata which yield the clue had been removed, with strata of 

 the Wellow type as the only Lias-Oolite deposit remaining, then 

 we should doubtless point it out as a good instance of a misch- 

 fauna, citing, as Ceyer does for Hierlatz, 3 the fact of the different 



1 III, 1, p. 712. 2 VIII, 1. p. 278. 



