32 TYPE AMMONITES— IV Feb. 



the Kimmeridgian, beginning a little earlier (about middle of Peri- 

 sphinctean), but ending sooner, probably not so late as Aulacosphinctcan. 

 Their approximate thickness of 4,000 feet is a scale by which to measure 

 the time taken to deposit the Kimmeridgian Beds. Yet this may not be 

 the fullest thickness laid down during the Ages involved — that can only 

 be ascertained when maxima are known for the deposits of each hemera. 



Whether there are too many or even, possibly, too few hemerae in 

 Table III will depend very much on methods of individual work influ- 

 encing individual opinion. For if fauna a be taken as a faunal index, 

 and then, because fauna b be found with fauna a at a certain place, the 

 assumption is made that fauna b is equally good as evidence for hemera a, 

 and further, if the same honour be claimed for c because that is found 

 occurring with b, it may happen that the assumptions of such an investi- 

 gator become altogether erroneous. He thinks that he is proceeding 

 horizontally, while all the time he is moving up an inclined plane. Such 

 a deception may be the more easy because the lithic facies can also be 

 moving up an inchned plane (S. Buckman, Jur. Chron. 11, O.J.G.S. 

 LXXVIII, 414). Faunal analyses should be one method of detecting 

 such deceptions. 



Authors would greatly facihtate the collection of data necessary for 

 faunal analyses and for proving or disproving hemeral sequences, by 

 summarizing and especially by clearly tabulating their results. To read 

 through pages of a paper in one's own language in search of details 

 which could and should be collected and tabulated in one page is no 

 light task : added to it is the risk of mistaking the author's meaning. 

 To do the same even in a familiar foreign language is a matter of 

 greater difficulty and greater risk. To accomplish it in the case of an 

 unfamiliar language means the employment of an interpreter familiar not 

 only with the language, but with its special scientific phraseology. 



Properly-presented Tables ought, whatever language their author 

 uses, to give their salient features to any reader, whatever his nationality. 

 The greater the classical basis and the less the national basis of the 

 language employed in the Tables, the more universal would be their 

 appeal. Scientific jargon could be so presented that the less intelhgible 

 it were to the layman of the author's nationality, the more intelligible 

 would it be to the scientific reader of any nationality. The world is not 

 yet settled enough for this — the nationality instinct is still too strong ; 

 but for technical tables there is much which could be said in its favour. 

 At any rate, whether in technical language or otherwise, tables of results 

 should be given : they should be clear and they should be uniform. 

 Sections or sequences should not be, in the same page, or even in the 

 same paper, first in ascending and then in descending order. One or 

 other order should be chosen for the paper and adhered to. My prefer- 

 ence is for descending order, so that the printed page and the quarry-face 

 correspond. 



