WOODWARD HIPPURITIDiE. 59 



The corrugations of this fossil are not superficial furrows, but are 

 foldings of the shell-wall, and project internally almost as much as 

 the hinge-inflections. 



Locality : Bakhtiyari Mountains. 



4. HiPPURITES VESICULOSUS, n. sp. PI. IV. fig. 6. 



Upper valve unknown : lowei' valve conical, furrowed lengthwise 

 with regular shallow grooves (at most 2 lines wide) ; cardinal inflec- 

 tions scarcely marked externally ; outer shell-wall 4 lines thick at 

 most ; ligamental inflection deep and very narrow ; muscular inflec- 

 tion short, round, and constricted ; siphonal inflection deepest ; inner 

 shell-layer composed of vesicular plates. 



Length (of a fragment) 8 inches, diameter 1^4 inches. 



Locality : Bakhtiyari Mountains. 



5. Radiolites Mortoni, Mantell sp. PI. V. figs. 1, 2. 



Upper valve unknown : lower valve found usually in groups ; in- 

 versely conical or elongated, the free surfaces ribbed lengthwise ; 

 ribs narrow (about 1 line in breadth), subequal, angular, in pairs or 

 groups ; shell-wall very thick, entirely composed of large and regular 

 cells ; rim slightly inclined, impressed with a few radiating dicho- 

 tomous lines in which the cells are transversely oblong ; inner layer 

 usually wanting, leaving a smooth cavity, originally partitioned off 

 below into large irregular water-chambers, and furnished with two 

 striated dental pits, close to the side, and separated by a wide in- 

 terval. 



Length of fragment 1 foot, diameter 6 inches ; shell-wall 2 inches 

 thick. 



Found in the Upper and Lower Chalk of Kent and Sussex *, and 

 in the Upper Greensand of Cambridge and Warminster. A fragment 

 of the rim apparently of this species, from Gosau, measures 4 inches 

 from the inner to the outer edge (British Museum). The Radiolites 

 Austinensis of Dr. F. Romer, from Texas, is probably identical 

 (Romer's Texas, t. 6. f. I). 



Radiolites Mortoni is the only British fossil of the family Hippii- 

 ritidcB at present known; it was noticed in 1833 by Dr. Mantell, 

 in his * Geology of the South-East of England.' In 1836 it was 

 again figured and described by Mr. Hudson (as a Conia) in the 

 * Magazine of Natural History' (vol. ix. p. 104). Several figures 

 are given in the 26th Plate of Mr. Dixon's posthumous ' Geology of 

 Sussex,' but these figures only represent the general form and mode 

 of aggregation, and there is no accompanying description. 



Dr. J. E. Gray, who gave an account of these fossils in the * Ma- 

 gazine of Zoology,' observed the OstrecB and 8pondyli growing far 

 down their cavities, and remarked that, if there had ever been an 

 internal shell-layer, it must have been removed whilst they were still 

 in the position where they grew on the bed of the sea f. In the 



* Remains of this species have been found in the Chalk at Lewes, in Sussex, 

 at Purfleet, Essex, and at Gravesend, Durham, and Lenham, in Kent, 

 t Magazine of Zoology and Botany, 1838, vol. ii. p. 228. 



