INTRODUCTION. 
NXl 
new species of yautihis (lY. Libanoticus) from the Upper Cretaceous 
of Lebanon was described and figured. This species is particularly 
interesting, from the fact that many of the specimens representing 
it in the Collection hare one or other of the beaks or mandibles of 
the animal attached to them on the ventral (convex) side of the 
body-chamber. Two of the beaks are figured separately at p. 305 
of this volume ; but I have added (p. 371) a figure of an upper 
mandible attached to a specimen of yautihis Libanoticus^ in the 
position above described. This is, I believe, the first figure of the 
kind published. 
I may also mention that an enlarged figure (fig. 73), showing the 
different layers composing the siphuncle of Aturia^ will be found 
at p. 338, to illustrate the description of those layers and their 
relationship with similar layers found in the siphuncle of yautihis 
pompilius. 
The Supplement to the present volume (pp. 378-399) contains 
descriptions of species recently added to the Collection, with some 
few inadvertently omitted ; also notices of recent works on the 
Xautiloidea, particularly Dr. Lindstrdm's valuable memoir on the 
Ascoceratidee and Lituitidee of the Silurian rocks of Gothland. 
I may here state that all the illustrations of the present volume 
were drawn by myself on the wood, the outlines being first made 
with the aid of a camera so as to ensure accuracy of proportion in 
the figures. 
It only remains for me now to express my great indebtedness to 
all those who have aided me in the performance of my present task. 
I have to tender my sincere thanks to Dr. Paul Fischer, of the 
Museum of Natural History, Paris, and also to the authorities of 
the AVoodwardian ^Museum, Cambridge, and the Museum of Practical 
Geology, Jermyn Street, for the loan of valuable specimens from the 
Collections under their charge. To Professor K. A. von Zittel and 
his colleagues in the Palaeontological Museum in Munich I am much 
indebted for the many facilities afforded me while studying there 
in 1889 ; and I am similarly beholden to M. Dollo, of the Iloyal 
Museum of Natural History in Brussels, whose good offices were 
extended to me while I was in the latter city in the same year. 
