248 DR. A. E. TRUEMA1N" 01S - THE [vol. lxXlV, 



my disposal his carefully collected material from the Dorset cliffs, 

 while other specimens have been lent by Mr. S. S. Buckman, 

 Mr. L. Richardson, Mr. J. W. Tutcher, and Mr. C. H. Watson. 



Mr. C. P. Chatwin directed my attention to the Napton 

 (Warwickshire) exposure, and this led to the discovery of an 

 important series of ammonites. 



For permission to examine material, and for assistance while 

 working in the various museums, I am indebted to Mr. Gr. W. 

 Lamplugh and Mr. H. A. Allen (Jermyn Street Museum), Dr. A. 

 Smith Woodward and the late Mr. Gr. C. Crick (British Museum — 

 Natural History), Mr. E. E. Lowe (Leicester), Mr. A. Smith 

 (Lincoln), Prof. J. W. Carr (Nottingham), Mr. T. Woodhouse 

 Parkinson (Whitby), Mr. S. E. Harrison (Cheltenham), and 

 Mr. H. Woods (Sedgwick Museum, Cambridge). 



In the field, help has been given by Mr. W. E. Howarth 

 (in Lincolnshire and Yorkshire), bv Mr. J. T. Sewell (Whitby), 

 Mr. J. W. Gray (Cheltenham), and Mr. C. H. Watson (Napton). 



Prof. T. F. Sibly kindly read my manuscript, and offered various 

 suggestions ; while Prof. Gr. Norwood and Mr. C. Brett have helped 

 with the nomenclature. 



My special thanks are due to Prof. H. H. Swinnerton for his 

 continued advice and encouragement, and to Mr. S. S. Buckman 

 for the help that he has so readily given in numerous ways. 



II. Historical Notes. 



Early in the last century Sowerby figured two ammonites which 

 he called Ammonites lienleyi and A. bechei, while Reinecke 

 described a somewhat similar form as A. striatus. While these 

 species are in themselves quite distinct when fully understood, 

 there are so many apparently intermediate stages that it is not 

 surprising that confusion quickly arose in the use of the names. 



Thus A. d'Orbigny's A. lienleyi (3, 1 pi. lxxxiii) is an ammonite 

 which I consider to be closely related to those forms that have 

 been called A. striatus Reinecke, while A. henleyi Reynes 2 is 

 unlike any English fossil that I have seen. Similarly, a number 

 of the specimens figured by Quenstedt (4, pi. xxix) are allied to 

 A. nautiliformis J. Buckman, a member of quite a different series. 



The naming of the Capricorn ammonites presented similar diffi- 

 culties: for, until the different species are closely compared, they 

 appear to be very similar. The three best-known species are 

 A. capricomus Schlotheim, A. latcecosta Sowerby, and A. macu- 

 latus Young & Bird; the first name has been most frequently 

 used. E. F. Schlotheim 3 in describing this species gave no figure, 



1 These numbers in parentheses refer to the List of Literature, § VIII, 

 p. 293. 



2 P. Reyn&s, ' Essai de Geologie & de Paleontologie Aveyronnaises ' 1868, 

 p. 88 & pi. i, figs. 2a-2b. Compare Mgoceras spoliatnm, K. Futterer, ' Die 

 Ammoniten des Mittleren Lias von (Estringen ' Mitt. Bad. Geol. Landesanst. 

 vol. ii (1893) pi. x, fig. 1. 



3 'Die Petrefactenkunde ' 1820, p. 71. 



