234 Correspondence — Mr. A. J. Juhes-Broicne. 



and without drawing in the least on that " scientific imagination " 

 with which my distinguished friend is kind enough to credit 

 me, and relying only on the use of my reasoning faculty, 

 I maintain that they must be carried down to the lowest levels 

 shown by the soundings, since rivers only flow at the bottom of 

 their valleys ! And, in this connection, let me ask Mr. Hudleston 

 with reference to his plan of the Gulf of Gascony and his isobathio 

 contours of 100 fathoms and 1,000 fathoms of the Fosse de Cap 

 Breton (p. 151), why has he left the latter in so incomplete a state ? 

 The 1,000-fathom contour is broken in two just above the point 

 where the narrow channel of 1,500 fathoms opens out on the abyssal 

 floor, as will be seen by reference to the map itself. Surely 

 with so many soundings there can have been no great difficulty in 

 carrying the 1,000-fathom line eastwards to the point of crossing, 

 which would indicate the form of this remarkable sub-oceanic ravine ; 

 and if contours of intermediate depths (say 750, 500, and 250 

 fathoms) had been ti'aced, they would have thrown additional light 

 on its form and character. As it stands, Mr. Hudleston's map is 

 unintelligible, and reminds me of that of M. Elisee Eeclus, who 

 leaves the mystery of the Fosse de Cap Breton unsolved. 



Edwaed Hull. 

 April 7, 1899. 



THE ASSOCIATION OF SGHKEJSfBAOSIA INFLATA WITH 

 SOPLITES INTERRUPTUS. 



Sir, — In discussing " The Base of the Gault in Eastern England " 

 (GEOLOGICAL Magazine, April, p. 161), Mr. A. M. Davies refers to 

 the mixture of Lower and Upper Gault species at Heath, near 

 Leighton Buzzard, and remarks that the same mixture " appears to 

 exist in the Isle of Wight, where S. inflata occurs in the Gault Clay 

 along with H. inter rwptus,'" his authority for this statement being 

 the Geological Survey Memoir on the Isle of Wight. 



It is true that in the tabular list of fossils at the end of that 

 Memoir (p. 279) Am. rostratus and Am. interruptus are entered in 

 the Gault column with the indication that both were found 

 at Compton Bay, but it is not stated in the text that they were 

 found in association. It so happens that I have had occasion to 

 investigate this very point, and discovered that Mr. Ehodes had only 

 found H. interruptus in the lower 20 feet of Gault, that a specimen 

 obtained between 73 and 93 feet from the base was H. denarius, and 

 that the S. rostrata came from a still higher bed, namely, that given 

 at 8 feet thick in Mr. Strahan's section on p. 63 of the Memoir. 



Other specimens of H. interruptus have been found in other parts 

 of the island, but always in the lowest part of the Gault and never 

 in association with S. rostrata. There is no mixture of zonal species, 

 but the upper part of what is referx'ed to ' Gault ' by Mr. Strahan 

 and others belongs to the zone of S. rostrata. 



At Heath, on the other hand, there is unquestionably a com- 

 mingling of Lower and Upper Gault species, and I am quite unable 

 to explain it unless the Upper Gault should turn out to be much 



