xciv INFERIOR OOLITE AMMONITES. 



A. Pauckostat.k. 



1. Platygeaphoceras careatinum, 8. BucJeman. Suppl., Plate XX, figs. 16 — 18. 



Description. — Subplaty-subpachygyral ; l sublatumbilicate ; comiaticostate, with 

 nodate junctions. 



Locality and Stratum. — Dorset: Bradford Abbas, Fossil Bed, upper part. 

 Bate of Existence. — Discitse hemera. 



2. Platygraphoceeas latum, 8. BucJeman. Suppl., Plate XX, figs. 19 — 21. 



Description. — Subplaty-subleptogyral, sublatumbilicate, comiaticostate. 

 Distinction. — From P. carbatinum, thinner and more closely costate. 

 Localities and Strata. — Dorset : Bradford Abbas, Fossil Bed, presumably upper 

 part, fairly common. Stoke Knap, Building Stone. 

 Date of Existence. — Discitse hemera, presumably. 



3. Platygraphoceeas apertum (S. BucJeman). Plate X, figs. 10, 11 ; Suppl., Plate 



XV, fig. 23 ; Fig. 55 in text. 



1888. Liocebas apertum, This Monogr., PI. x, figs. 10, 11. 

 1902. Platygraphoceeas apertum, Emend. Amm. Noin., p. 4. 



Description. — Platyleptogyral, gradumbilicate, semicostate, i. e. striicostate. 



Distinction. — From P. latum, smaller umbilicus. 



Remarks. — Young forms (25 to 40 mm. diameter), including therein those 

 slightly more and slightly less umbilicate than the type, are common. They show 

 pointed lateral lappets at different sizes : in one case the lappet is 8 mm. long and 

 incomplete. No counterpart, however, of the type in size has been found. 



Locality and Stratum. — Dorset: Bradford Abbas, from the Fossil Bed, pre- 

 sumably from the upper part. Stoke Knap, in the Building Stone. 



Date of Existence. — Discitse hemera, probably. 



4. PLATYtiBAPHOC'ERAS, sp. A. Plate XV, figs. 9, 10. 



1889. Lioceras apertum, This Monogr., PL xv, figs. 9, 10. 

 k This differs from type P. apertum in being thicker, having more 



gibbous-sided whorls, and stronger ribs. 

 > Localities and Strata. — Dorset: Bradford Abbas, apparently 



lower part of Fossil Bed. Sandford Lane, near Sherborne, in 

 line of maty. greyish sandstone, below the Hyperlioceras horizon. 



grapnoceras. ° J ' ' 



s i>- A - Date of Existence. — Conca.vi hemera. 



1 In this and other cases the difference of terms between the description of the species and the 

 definition of the genus is due partly to the age of the specimen, and partly to the stage of specific 

 development in relation to the species selected as the type of the genus. 



< 



N 



Fig. 56.— Radial 



