" UPPEK-LIAS CLAY " OF DOWIf CLTPPS. 519 



This blue clay or marl lying heloiv the Yeovil Sands contains 

 Dumortieria radians ; but the position of the same species in the 

 Cotteswolds is in the limestone above the Cotteswold Sands *. In 

 other words, the blue clay of Down Cliffs is contemporaneous with 

 the limestone above the Cotteswold Sands of Gloucestershire ; yet the 

 former is called " Upper Lias," while the latter has been placed in 

 the " Inferior-Oolite Series." 



The names themselves are of no importance. The cause of com- 

 plaint is that the same palseontological horizon should receive two 

 names, causing it to appear of earlier date in one place than in the 

 other. 



It is possible to obtain a fairly complete section, from the Middle 

 Lias to the top beds of the Inferior Oolite, by superposing upon 

 Down Cliffs the Chideock Hill, which lies just inland to the north ; 

 and the following is the result : — 



Section at Chideock Hill and Down Cliffs, 



ParJcinsoni- 1. Pale and somewhat shelly limestone, with FarJcin- ft. in, 

 zone. sonia ParJcinsoni, Terehratula sphceroidalis, Wald- 



heimia Meriani about 9 



2. Brown limestone, with small grains 1 9 



Concavum- 3. Yellow limestone, with very coarse, almost jiisoli tic, 



zone. brown grains; in places much disintegrated ... 1 3 



MurchisoiKB- 4, Yellowish limestone, with small dark grains ; 

 zone. Ludwigia MurcMsoncB, Lioceras hradfordense, 



Lytoceras Wrighti visible for 3 6 



5. Small part unseen. 

 Opalinum- 6. Yellow sands and calcareous sandstone, with Lio- 

 zone. ceras O'pal'mum, capping the 



Down Cliffs. 1^; if^owstndswithZ)^«/^(>r^f^mc.m^/^^^ ("^^^ ^^^ ^ 



Jurense-ZQTVQ. j g^ -g^^^ micaceous (?) shale, altogether more com- 

 pact. D. radians^ and a coarser-ribbed species 



of the genus, possibly D. Levesquei about 70 



Commune- 10. Mottled, pink and cream-coloured limestone 

 and Fcdci- in two layers ; as may be seen from fallen blocks, 



ferum-zones. Hildoceras hifrons is dominant in the upper layer, 



and Harpoceras falciferum in the lower 10 



Spinatum- ?11. Ironshot limestone, much stained in places ; 

 zone. Bhynchonella fiiTcillata 7 



Note. — Bed 9 is more clayey below ; and, as it passes upwards, becomes moi'e 

 of a marl. The Ammonites were found some distance down (12 feet and more). 

 Nothing was discovered in the lower part of the bed ; but, of course, it is 

 possible that the lower part may contain different species of Ammonites. 

 When compared with the Cotteswolds, it is seen that the horizons called Dis- 

 pansum-, Striahdmn-, and Variabilis-heds — the latter being equal to the Cottes- 

 wold Sands — should come between the Commune-zone and the Dumortieria- 

 beds, that is to say, somewhere in the lower part of Bed 9, or, it may be, partly 

 in Bed 10. 



The section of Chideock Hill differs in one noticeable particular 



* The limestone-capping of the Cotteswold Sands, usually called the 

 Cotteswold Cephalopoda-bed, contains four Ammonitiferous horizons, namely 

 (in descending order) Moorei-, Duniortieria-, Dispansum-, Sfriatuhcm-heds. It 

 is in the second of these that J). radians occurs. 



