76 THE FOSSIL ECHINOIDEA 



although it is quite possible that it may be the young stage of a well-defined variety of 

 P. pileus. 



Genus NEOCATOPYGUS, gen. nov. 



Test of moderate size, tumid and high, subrotund marginally, greatest height 

 posteriorly eccentric. Abactinal area convex, sides tumid and high ; actinal surface 

 convex. Posterior extremity subrostrate and prominent, tumid actinally. 



Ambulacra petaloid, petals short and subequal, open at the extremity ; poriferous 

 zones subequal, pores unequal and conjugate. Extrapetalous pores single. 



Peristome small and pentagonal, eccentric in front. Floscelle well developed ; 

 bourrelets forming an ornamented wall-like rim ; phyllodes with an inner series of 

 supplemental pores. 



Apical disk small and compact, slightly eccentric in front ; four generative pores ; 

 madreporiform body placed centrally. 



Periproct small, subcircular or oval, supramarginal, placed at the extremity of the 

 posterior rostration, by which the aperture is slightly overhung. The subanal area, 

 which is tumid and rostrate, is faintly grooved. 



Tubercles small, perforate and crenulate, sunken in deep scrobicules, intermediate 

 space granular, the encircling ring of the scrobicule often well defined. Actinal orna- 

 mentation coarser than above the ambitus. 



This genus recalls Catopygus to a certain extent, but is readily distinguished by 

 the form of the test, the small ambulacral rosette, the single series of extrapetalous 

 pores, the character of the floscelle, the position of the periproct, and the character of 

 the posterior rostration. 



The form is well defined, and further comparison with other genera of Echino- 

 lampinse seems superfluous. 



The forms included in this genus difl'er much from the modem Catopygi, and are 

 as remote from them as from the Cretaceous forms. 



1. Neocatopygus eotundus, sp. nov. Plate XVI, Figs. 1-10. 



The test is very tumid, broadly oval or cordiform in marginal outline, rounded in 

 front, rather pointed behind, broadest at a lateral projection, which is anterior to a 

 narrowing immediately anterior to the faint subanal rostrum. The test is highest 

 posteriorly midway between the distal ends of the posterior lateral ambulacra, and it 

 slopes gradually in front to the very tumid ambitus, and more suddenly posteriorly to 

 the periproct, which is three quarters of the distance from the upper part of the test to 

 the lower ; thence the outline of the test, passes obliquely downwards and forwards. 

 The sides of the test are tumid, and slope up gradually to the apex, and more suddenly 

 to the slightly convex actinal surface. The apical surface is convex ; and the convexity 

 of the posterior interambulacral area is iliterfered with, along the median line behind 

 the point of greatest height, by a shallow groove with faintly raised edges. This groove, 

 with its edges, becomes slightly raised near the periproct ; and the structure is continued 



