1867.] TATE — SOXTTH-APEICAiq- FOSSILS. 155 



Placunopsis subjueexsis, spec. nov. PL IX. figs. 1 a, 1 b. 



Shell orbicular, irregular, thin ; free valve rather oblique, exceed- 

 ingly gibbous; umbo submarginal, obtuse, and depressed; orna- 

 mented by numerous, fine, regularly nodulous, waved costse, crossed 

 by numerous delicate concentric stria3, and a few well-marked lines 

 of growth. 



Dimens. Length IJ inch. Height l^ inch. 



The species of the genus Placunojms have such a general re- 

 semblance one to another, both in form and ornamentation, being 

 moreover necessarily more or less variable in shape, that it is often 

 difficult to recognize constant distinctive characters. The present 

 species has for its representative P. Jurensis of the Lower Oolites of 

 Europe, and dififers from it in its greater gibbosity and obliquity, 

 and in possessing regular knotted ribs. 



Log. Collected by Dr. Eubidge in some abundance at the Zwart- 

 kop Eiver Heights, in a yellowish sandy shell-rock. 



Placuxopsis tjndulata, spec. nov. PI. IX. fig. 2. 



Shell orbicular, thin, irregular, nearly equilateral ; convex, gib- 

 bous or depressed ; apex marginal, obtuse, and depressed, ornamented 

 by numerous concentric waved rugae. 



Dimens. Length 14- inch ; height -^ of an inch. 



Loc. In yellowish-grey limestone, Mouth of Sunday's Eiver (Ric- 

 hiclge) ; and four specimens adherent to a piece of mineralized wood 

 (calcareous with glauconitic grains) perforated by Gastroclicena domi- 

 niealis^, Sharpe. 



Pectef RiTBinaEANUs, spec. nov. PI. YII. fig. 11. 



Shell inequivalve, ovately orbicular, convex, with nine or ten equal, 

 large, elevated, subacute and distantly arranged costse ; the intervals 

 are wide and ornamented with very fine concentric striae, which are 

 continued over the ribs. Auricles large and unequal. 



Dimem. Height -^ of an inch ; breadth -f^ of an inch. 



This Pecten presents the appearance, less the spinous processes, 

 of P. suhspinosus, Schloth., which ranges from the Inferior Oolite 

 to the Coralline Oolite of Nattheim ; other slight differencescan be 

 pointed out. 



Log, Dr. Eubidge has found this Pecten to be one of the most 

 frequently occurring shells, in a yellowish sandy shell-rock with 

 greenish-grey patches here and there, at Prince .-Ufred's Eest. 



Pecten peojecttjs, spec. nov. PL IX. fig. 6. 



Shell oblique, ovately orbicular, moderatel}^ convex, equivalve ; 

 remarkably inequilateral, the umbone being slightly curved ante- 

 riorly and the anterior side projected forwards. Yalves ornamented 

 with closely arranged dichotomous lines curving outwards ; the in- 

 terstitial spaces subpunctated. Auricles unequal, the anterior one 



* The specimen figured in Greol. Trans. 2nd S9r. vol. vii. pi. 23. fig. 4 a, is wood, 

 and not " bone," as stated at p. 198, op. clt. — T. R. J. 



VOL. XXIII.— PART I. W 



