86 THE FOSSIL ECHINOIDEA 



measures 21 millim. in length. The interporiferous zone is broad, and occupies nearly 

 the whole breadth of the floor of the groove ; it is narrower than a poriferous zone. 

 The angle made by the antero-lateral ambulacra is 120°. 



The postero-lateral ambulacra, 15 millim. in length, are straight, ovate-lanceolate, 

 deep and narrow, form an angle of about 55°; and their pairs of pores (about 30 in 

 number) are large, placed on the nearly vertical sides of the groove, and are separated 

 by wide costal projections. The interporiferous zone is large, and occupies the surface 

 of the ground-floor. 



The apical system is broken, and nothing satisfactory can be made out about the 

 number of the plates and pores ; but, from the large size of a posterior pore and the 

 very narrow ridge of the anterior interambulacrum, it is probable that there were only 

 one pair of generative pores. 



The anterior interradials have sharp keels, very narrow near the apex ; and the 

 plates near the ambitus are nodulose. The keel of the lateral interambulacrum is broad 

 and not very high, and that between the posterior petals is broad and enlarges posteriorly. 

 The posterior part of this interradial area is truncated, and forms an oval slightly re- 

 entering surface, high up in which is the large ovoid periproct. Faint traces of a peri- 

 petalous fasciole exist, which passes far in front over the ambulacrum, and which does 

 not enter far between the petals. The ornamentation is scanty, and consists of small 

 flat tubercles in slightly sunken scrobicules surrounded by circlets of miliaries. The 

 ornamentation is larger and scantier in front and beneath anteriorly. The tubercles are 

 perforate and crenulated and weathered. 



The height of the test is unknown ; the length is 2^- inches, and the breadth on 

 a level with the apical disk is the same. 



80 

 30- 



Locality. North-east of Band Vero, in the Eanikot series. Survey-number G f 



Illustration of the Species in Plate XX. 

 Fig. 9. The test, from above : natural size. 



Genus SCHIZASTER, Agasdz, 1836. 



Test cordiform, more or less inflated, high posteriorly and sloping to the front. 



Apical system eccentric posteriorly, often to a considerable degree. 



Ambulacra petaloid, unequal, sunken in deep grooves. The anterior pair flexuous, 

 directed to the front, and not very widely divergent ; the posterior pair very short and 

 slightly arched proximally. Poriferous zones equal, pores oblong and conjugate. The 

 odd ambulacrum sunken in a deep wide furrow, of which the margins form keels ; its 

 poriferous zones are long and composed of numerous pores, which may be disposed in 

 crowded pairs forming a simple series, or the pores may be so crowded as to form two 

 irregular series in each zone. 



