YORKSHIRE BASIN. 77 
yielded these Ammonites. At any rate, if these beds do not belong to the 
Humphriesianus-zone they must be lower in the series, possibly about the level 
of the Sauzei-subzone. 
In dealing with the Gasteropoda from these marine horizons of the Inferior 
Oolite in Yorkshire, it must be remembered that the majority of the species 
have been recently described and figured in the work referred to. The figures 
and descriptions there given will be incorporated, as far as may be convenient, with 
Part I of this Monograph. As a rule the Yorkshire specimens are not so well pre- 
served that close specific determinations can always be given with certainty. This 
constitutes one great difficulty when instituting comparison with the beautiful 
fossils of Dorsetshire. So long as we are satisfied with lumping, the resemblances 
and analogies hold fairly good, but when we come to splitting, the case is different ; 
and the difficulties are further enhanced by the difference of matrix. Under these 
circumstances an accurate comparison of the rare and difficultly preserved Gaste- 
ropoda of this district with those of the others, and especially of No. 1 district, 
is next to impossible. 
CoNcLUSION OF THE INTRODUCTION TO THE INFERIOR OoLitE GASTEROPODA. 
In concluding this introduction to the Inferior Oolite Gasteropoda, I must 
acknowledge my obligations to many gentlemen who have kindly assisted me. To 
Prof. Hugéne Deslongchamps of Caen my best thanks are due for the facilities 
afforded in studying his splendid collections from the Inferior Oolite of Normandy, 
and for much kind advice and sympathy. To him and to his father all students 
of Jurassic Paleontology are deeply indebted ; and the curious resemblance existing 
between the development of the Inferior Oolite in Normandy and Dorsetshire 
makes us Englishmen all the more conscious of our obligations to these two illus- 
trious savants, who have done so much in their day to render the publications of 
the Linnzan Society of Normandy famous. It has been my good fortune to have 
been enabled to purchase the collection of Inferior Oolite Gasteropoda formed by 
the late Prof. Buckman and his son Mr. 8. 8. Buckman. On the majority of 
these specimens the locality and horizon have been carefully indicated, and I am 
greatly obliged to Mr. S. S. Buckman for the readiness he has at all times shown 
in imparting any information required relative to the fossils and subdivisions of the 
Inferior Oolite. Mr. Witchell, of Stroud, has laid me under a deep obligation, not 
only by allowing me free access to his excellent collection of Inferior Oolite Gastero- 
poda from that part of the Cotteswolds, but also for his readiness in explaining 
the stratigraphy of the neighbourhood of Stroud. It is by the aid of his collection, 
in conjunction with that formed by the late Dr. Lycett, now preserved in the Jermyn 
Street Museum, that we may hope to increase our knowledge of the somewhat 
