630 Original Articles. [Oct., 



already quoted. He lias suggested that instead of the term 'con- 

 temporaneity,' we should substitute a word that would express 

 similarity of serial relation, but would exclude the notion of time 

 altogether, and has proposed the term ' homotaxis ' (similarity of 

 order) as embodying that idea, and as a parallel to ' homology,' which 

 is used in anatomy to express correspondence of position. This term 

 'homotaxis' was suggested in 1862, and as yet only one palaeonto- 

 logist of note, namely, Dr.* Duncan, has used it in his writings instead 

 of the terms ' contemporaneous ' and ' synchronous,' neither of which 

 conveys the exact meaning of those who, like myself, believe that the 

 absolute contemporaneity of distant deposits cannot be strictly 

 determined. But it is something for one high authority to have 

 " broken the ice " within three years. 



If ' homotaxis ' is to be used instead of ' contemporaneity,' we must 

 have its adjective, ' homotaxeous ' as synonymous with ' contempo- 

 raneous ; ' and I cannot see any reason why these terms should be 

 objected to on account of their novelty. Every new idea, like every 

 new machine, must have a new name ; and if the name has not been 

 given until the idea has become tolerably familiar to us, there is 

 greater reason why it should not now be objected to. There is also 

 this additional consideration, that if our inferences are based on the 

 ' homotaxis ' of formations instead of their contemporaneity, there will 

 be no necessity to " question every conclusion as it arises." 



EXPLANATION OF THE PLATE. 



Fig. 1. Cyrena fluminalis, fossil in the Post-pliocene deposits of England, Belgium, 



&c, recent in the Nile and some Asiatic rivers. Twice the natural size. 

 Fig. 2. Argonauta Mans, fossil in the Sub-Apennine deposits of Italy, and ranging 



in the recent state as far as China. Natural size. 

 Fig. 3. Ebuma spirata, fossil in the Miocene strata of Bordeaux, recent in the 



East Indian Ocean. Natural size. 

 Fig. 4. Voluta strophodon, M'Coy, MS., from the Miocene deposits of Australia. 



Natiu-al size. 

 Fig. 5. Voluta s2)inosa, from the Eocene beds of England and France. Natural 



size. 

 Fig. 6. Trigonia semi undulata, M'Ooy, MS., from the Miocene deposits of Australia. 



Natural size. 

 Fig. 7. Trigonia costata, from the Oolitic formations of England and the Continent. 



One-third the adult size. 

 Fig. 8. Adult Tertiary Oliva, from Java and Crete, apparently identical with the 



young of the existing Oliva utriculus. Twice the natural size. 

 Fig. 9. Full-grown specimen of Oliva utriculus, from -Africa, showing the adult 



characters. Natural size. 



