part 4] JUEASSIC CHEO^'OLOGT : LIAS. 287 



this species from Ammonites valdani D'Orbigny.^ Its whorls are 

 also somewhat broader and thicker. The proportions that he gives 

 are T. 95, 27, 17-19, 48. 



History of figured specimeoi^— Griven to me many ^^ears 

 a.go by the late Eev. F. Smithe, F.G\S., with other large species, 

 as having been found in the Middle Lias clays of Leckhampton 

 (Gloucestershii-e), when the Banbury & Cheltenham Kail way was 

 ■constructed. 



Family AEIETIDiE. 



Genus Eadstockiceeas,^ nov. 

 Tj^pe, R. compUcatum, nov. 



Definition. — Oxycone, highly involute, septicarinate ; peri- 

 phery concavifastigate. Radial line indistinct, laterally slightly 

 flexed ? slight curving forwards on outer third. Suture-line very 

 highly complicated — one line touching the preceding at so many 

 points as to make the separation of the chambers a ver}^ difficult 

 process. The peripheral lobe has two long branches, and five well- 

 developed branches penetrate the external saddle, four of them off 

 the side of the peripheral lobe ; the superior lateral lobe narrow- 

 stemmed, strongly trilobate, unequal; inferior lateral lobe broad- 

 stemmed, w^ith short lobules ; a considerable array of auxiliary 

 lobes. 



Distinction. — The high degree of specialization of suture-line 

 distinguishes this genus from Oxynoticeras. Involution is rather 

 more developed ; peripher}^ is on rather a lower grade, but is 

 beginning to show the knife-edge of that genus, while suture-line 

 is well beyond it : the array of lobes external to the superior 

 lateral lobe is greater in number and more developed, that lobe is 

 specialized into a long narrow-stemmed lobe of cruciform pattern ; 

 while it is the inferior lateral lobe which is in the same stage as 

 the superior lateral of Oxynoticeras — broadly U-shaped with short 

 lobules. 



Kadstockicebas complicattjm, sp. nov. (PL XXVII, figs. la& 

 1 h ; text-figs. 6, p. 294 & 12, 21, p. 295.) 



Description. — Oxycone ; subextremiplaty-leptogyral ; an- 

 gustumbilicate ; periphery concavifastigate, septicarinate ; sub- 

 distanti-obscuricostate, gammiradiate ; complicati-septate. 



G-eneral details. — The type is wholly septate : there are 

 indications of its having lost more than another half-whorl, so that 

 it was a giant of about 380 mm. or nearly 16 inches in diameter. 

 The periphery is not true knife-edge — the side falls into the keel 

 with a concave depression ; ribs are rather distant and obscure ; 

 greatest breadth is abc^t one-third from the umbilical border which 



^ ' Pal. fran?. : Terr. Jiir. Ceph.' 1844, pi. Ixxi & p. 255 

 ^ Radstock (Somerset). 



