179 



NOTES 



On Foreign Jurassic speciks of the genus PEDINA nearly allied to British 

 forms, but which have not yet been found in the english oolites. 



Pedina arenata, Agassiz. Echinoderra. Foss. Suisse, II, tab. xv, figs. 1 — 3. 



Test small, hemispherical, flat at the base, convex on the upper surface ; ambulacra 

 Avith two rows of marginal tubercles, placed apart and separated by fine granules ; 

 poriferous zones very narrow, trigeminal ranks nearly upright ; inter-ambulacra with two 

 rows of small primary tubercles, secondary tubercles very small and scarcely 

 apparent, except on the under surface ; miliary granulation more abundant and 

 distinct than in the other species ; centro-sutural line naked and conspicuous ; 

 mouth opening proportionately large, two fifths the diameter of the test, peristome 

 decagonal, and only slightly notched ; the size of the mouth opening distinguishes it from 

 other Pedinas. 



Dimensions. — Height, six tenths of an inch ; transverse diameter, one inch. 



Formation. — Collected from the Inferior Oolite (Bajocien) of Goldenthal (Jura 

 Soleurois). 



Collection. — M. Gressly, very rare. 



Pedina Gervillii, Desmoulins. Tableaux synonymiques des Echinides, p. 316, No. 19. 



Test sub-pentagonal, depressed ; ambulacra with two marginal rows of granules, 

 placed wide apart, a larger and smaller tubercle alternating on the same row ; in the structure 

 of the ambulacra the difference between this species and Pedina rotata is chiefly observed ; 

 inter-ambulacra with two rows of primary and four rows of small secondary tubercles ; 

 poriferous zones narrow, pores largely open, trigeminal ranks slightly oblique, mouth 

 opening small, peristome decagonal and deeply notched ; apical disc moderate in size, 

 genital plates nearly equal. 



Dimensions. — Height, thirteen twentieths of an inch ; transverse diameter, one inch 

 and one quarter. 



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