58 FAUNA OF THE CORNBRASH. 



keel and furrows are well marked ; the sigmoidal ribs are very uniform, 38 per 

 half-whorl, slanting forwards near the periphery and dying away toward the 

 umbilicus. The sutures are characterised by a pair of backwardly projecting 

 parallel teeth or lobes, with a saddle between, which does not rise so far forwards 

 as those within or without ; both sets are three in number, rising higher as either 

 edge of the whorl is reached, and slightly jagged. 



In another specimen (Fig. 5) from the same locality the umbilical half has a 

 slope towards the centre. The sides of the periphery beyond the furrows are 

 more swollen, the umbilicus is two-elevenths of the diameter, and the greatest 

 thickness in the centre of the whorl is '28. A third specimen (Fig. 6) has some 

 sign of the collection of the ribs into groups ; its thickness is only "24 of the 

 diameter, consequently the sides are flatter. The umbilicus is one fifth of the 

 diameter. The sutures are of the same type. 



All these specimens are of small size, and their most remarkable feature is the 

 variation of the size of the umbilicus from one eighth to one fifth of the diameter. 

 This recalls the character of G. ptychophorum, but in most cases it may be only 

 characteristic of an early stage of existence. In this view these small forms 

 would be the young of either discus or hochstetteri. M. Bigaux says that discus 

 has no furrows in the } 7 oung of the same size, but it has something that would 

 easily become such if a little deeper. The real difficulty is that the sutures do 

 not agree at the same size, though we know of no hochstetteri so small as legayi. 

 Nevertheless, there is a specimen from Thrapston which has sutures approximating 

 to those of hochstetteri and the furrows on either side the keel approximate to 

 those of legayi. 



Distribution. — This species has been found at Sudbrook (2), Eushden (1), 

 Trowbridge (1 ?), Holwell (2), and Thrapston (1 ?). 



Order BELEMNOIDEA. 



The occurrence of Belemnites in the Cornbrash appears to be doubted, as 

 none are mentioned in H. B. Woodward's list except a " sp." from Dorsetshire, 

 while Fox-Strangways records them with a query. The actual records are : 

 Belemnites toniatilis (6, 28) ; Bel. sp. (43). 



The first of these refers to the Belemnites found in the " clays of the Corn- 

 brash " in Cayton Bay. Phillips states, in his first edition of the ' Geology of 

 Yorkshire,' that " no Belemnites have been found in the Cornbrash of Yorkshire," 

 but in 1835 this statement becomes "Belemnites are rare in the Cornbrash 

 cf Yorkshire." Leckenby, writing on the Kelloway rock (25), records B. toniatilis 



