444 MR. S. 8. BUCKMAN ON THE BAJOCIAN [-A-Ug. 1 89 5, 



non-ammonitiferous Jurassic deposits. Once a starting-point is 

 obtained in a record of contemporaneity with ammonites at certain 

 type-localities, the rest becomes an easy matter. 



The brachiopod-fauna of the Cotteswolds is, on the whole, abun- 

 dant. Compared with Dorset, the species are certainly fewer — less 

 than one-half in my opinion, allowing for those und escribed — but 

 individuals are undoubtedly more numerous : a rough estimate would 

 place them at twice as many. This fact, added to the far greater 

 accumulation of deposit in the Cotteswolds as compared with Dorset 

 — often as many feet in the former as there were inches in the 

 latter, — enables the collector to localize his horizons with very con- 

 siderable ease and decided precision. 



In order to show what has been done in this way I append 

 (pp. 440-443) a table of the chronological sequence of brachiopoda 

 in the Cotteswolds, and in Dorset-Somerset. 1 In regard to the latter 

 the records are the result of my own work. They may in some 

 cases require revision, because the specimens were mostly collected 

 before so many divisions were attempted. In the Cotteswolds the 

 records are in the main also the result of my own work ; but I 

 have had the great advantage of Mr. Upton's help in confirmation. 

 Of Cotteswold brachiopoda Mr. Upton possesses a magnificent col- 

 lection ; he has been most precise in recording localities, and very 

 observant in the matter of horizons ; while he is equally discrimi- 

 nating in regard to species. Therefore I drew up this table and 

 submitted it to him in MS. Certain additions are made on his 

 authority, and to these his name is appended in square brackets 

 — the same sign being used for any authority for horizon in other 

 cases. 



A comparison of the two sides of Table VII. shows that I have 

 tabulated about 50 species for the Cotteswolds and 65 for Dorset ; 

 but the latter number is far fewer than that district is entitled to. 

 I have collected in the Cotteswolds for a far greater number of years 

 than in Dorset, and owing to the accessibility of certain places in the 

 former region, on account of its proximity to populous towns, its 

 strata have always received a very large amount of attention. The 

 number of undescribed Cotteswold species is, therefore, somewhat 

 small ; but the number of undescribed Dorset species is very large. 

 Taking a rough and, I think, by no means exaggerated estimate of 

 the number of species in the two regions, the Cotteswolds would 

 show about 60 to 65 forms and Dorset 100 to 120 or more. These 

 numbers take no account of what may be called the ' micro- 

 brachiopoda,' Theeidium, Zellania, etc., which, if anyone were to 

 undertake their systematic investigation, would, I know, prove to 

 be abundant in both regions. 



Further investigation of the brachiopod-faunae of Dorset-Somerset 

 and the Cotteswolds shows how very little in the way of correlation 

 can be done by a direct comparison thereof during certain particular 

 hemerse. Thus only three species are common to both regions in 

 the time of the Murchisonce hemera ; after that there are hardly any 



1 The district south of the Menclips. 



