EOHINOIDEA. 23 



The ambulacral areas, flush with the test, are narrowly lanceolate, limited to 

 the upper surface, subpetaloid, and unequal in size ; the single ambulacrum is short 

 and broad, the an tero -lateral pair broader and a little longer, the postero-lateral 

 pair considerably narrower, but at the same time longer than the former. In the 

 single ambulacrum the poriferous zones are slightly curved and consist of an equal 

 number of pairs of pores ; the inner pores are round, the outer elongated and 

 conjugated to the former by a fine sulcus ; on the narrow ridges between each pair 

 of pores there is a row of 3 to 4 minute granules. In the antero-lateral ambulacra 

 the poriferous zones are more strongly curved, the anterior zone being slightly 

 shorter than the posterior one ; in the postero-lateral pair the poriferous zones are 

 only slightly curved, the posterior zone being narrower and considerably shorter 

 than the anterior one. The pores are the same as in the single ambulacrum. At 

 the lower end of the petals the pores become smaller, and are set wider apart 

 as they pass round the border of the test to the peristome. 



The peristome is subcentral slightly nearer to the anterior border, pentagonal, 

 elongated in longitudinal direction and surrounded by a well developed floscelle. 



The buccal petals are rather large, broad and nearly closed ; their poriferous 

 zones are well developed, but have not many pores, which are apparently of the 

 same number in both rows. The posterior petals are shorter and broader than the 

 anterior ones, which are the same length as the odd one. 



The interambulacra end actinally in short rounded bourrelets which are covered 

 on the sides with an exceedingly delicate granulation. 



The longitudinal periproct is very small, pyriform, situated above the posterior 

 border in such a way that it is neither visible from above nor below ; the upper 

 edge is slightly overhanging. 



The ornamentation of the upper surface is very homogeneous and consists of 

 numerous minute tubercles sunk in a deep scrobicule ; on the lower surface the 

 tubercles suddenly increase in size towards the centre, not covering, however, a 

 rather broad band which extends from the posterior interambulacral bourrelet 

 to the posterior border ; in front of the mouth this band is short and not so well 

 marked as behind ; under the magnifying lens numerous delicate granules can be 

 seen on this band. 



Locality and stratigraphical position. — D^s Valley; horizons Nos. 2 and 4, 

 Mazar Drik ; horizon No. 8. 



Bemarhs, — It will be seen from the above description that one of the peculiar 

 features of this species is its lower surface ; only in one specimen is it slightly 

 concave in the centre ; in all the others it is flat, even slightly convex. As regards the 

 ornamentation of the lower surface it differs in this respect from all the other species 

 known to me. The peculiar band extending from the posterior border to the 

 mouth, and for a short distance beyond it, covered with minute tubercles, bordered 

 on either side by areas covered with rather large tubercles sunk in deep scrobieules, 

 increasing in size towards the centre, gives this species an appearance quite like a 

 Ccissidulus, 



