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On some new Species o/ Hemipedina /ro/w the Oolites. 

 By THOMAS WRIGHT, M.D., F.R.S.E. 



SINCE the publication of our paper in the August Number of 

 the 'Annals and Magazine of Natural History,' on the new 

 genus Hemipedina and the Synopsis of the species included 

 therein, our friend S. P. Woodward, Esq., has kindly sent us 

 three new English forms of this group, one found in the cal- 

 careous grit of Berkshire, and two in the Kimmeridge clay of 

 Bucks ; our friend Thomas Davidson, Esq., has likewise com- 

 municated a figure of one found by M. Bouchard Chantereaux 

 some years ago in the Kimmeridge clay of Boulogne-sur-Mer ; 

 we lose no time therefore in recording these additions to the 

 Oolitic fauna, at the same time returning our hearty thanks 

 to the kind friends who have so liberally communicated the 

 specimens. 



A. Species from the Calcareous Grit. 

 Hemipedina Marchamensis, Wright, nov. sp. 



Test large, and depressed ; ambulacral areas narrow, with two 

 rows of marginal tubercles, nearly as large as those of the 

 interambulacra, extending regularly and without interruption 

 from the peristome to the apical disc, and separated by a zig- 

 zag line of small granules down the centre, the areas retain- 

 ing a nearly uniform width throughout ; poriferous zones form 

 a slightly waved line, from every three pairs of pores being set 

 slightly oblique to the line of the zones ; interambulacral areas 

 four times the width of the ambulacral, with eight rows of 

 tubercles at the equator, each tubercular plate supporting 

 four nearly equal-sized tubercles abreast ; bosses prominent ; 

 areolas surrounded with incomplete circlets of small granules ; 

 mouth-opening less than one-third the diameter of the test ; 

 peristome unequally decagonal; five jaws, in situ, each jaw 

 having two broad flat central ridges, and two oblique mar- 

 ginal ridges with two intervening depressions ; teeth long, and 

 obliquely truncated at the points. 



Dimensions. Transverse diameter 2 T 9 TT inches; height ly 5 ^ 

 inch ? 



Locality. The calcareous grit of Marcham, Berks. 

 Coll. The Hon. R. Marsham. 



