OF WESTEEN SIND. 63 



not very numerous, are oblique, conjugate, with well-marked intermediate ridges ; and 

 their pores are large, circular or slightly elongate in outline, and subequal in the 

 pairs. The interporiferous zone is widest towards the half-distance from the apex. 

 The postero-lateral ambulacra are narrower than those just described, and either slightly 

 longer than or equal to them ; and the width of the poriferous zones is less. They 

 form an acute angle at the apex, and are nearly closed distally. The pores are oblique. 

 A single row of wide-apart pores passes over the margins from each poriferous zone ; and 

 at the peristome the rows approach to form a rudimentary phyilode whose pores are at 

 the sutures of the plates ; and there is no doubling of them. The ornamentation of the 

 petaloid areas is the same as that of the surrounding test, and consists of numerous 

 small sunken scrobicules, with short and broad tubercles in them. 



The interradial areas are largely developed abactinally. The anterior are marked 

 by a larger ornamentation than elsewhere ; and the posterior is rounded between the 

 ambulacra and narrow, but it does not form a decided keel ; it is slightly pinched in 

 near the margin, on either side of the line leading down to the periproct. 



The peristome is at the deepest point of the actinal concavity, large, widely open, 

 deep, transverse, and elliptical in outline, the smallest angles being at the sides. A process 

 composed of the inner parts of the plates around the peristome passes upwards like a 

 short canal ; and its surface is minutely granular. The ambulacra of the peristome are 

 narrow ; and the first two plates have each a pore on them, which penetrates the plate 

 and looks into the canal just mentioned. The other plates are narrow, and gradually 

 become broader towards the margin. 



The edge of the peristome between the phyllodes is slightly raised, and in the 

 natural position projects slightly downwards. The ornamentation of the actinal surface 

 of the test is slightly larger than that of the upper part ; and there is a small knob close 

 to the peristome on either side of the ambulacra. 



There is a faint groove in front of the peristome ; and the anterior margin is slightly 

 incised by it in young specimens. The periproct is supramarginal or marginal, small, 

 and is slightly overhung by the faint keel. 



Length of specimen (Figures 11 & 12) -/q inch, breadth -^q inch, height -po >' length 

 of a second specimen -^ inch, breadth -^^0 inch, height -j^ inch ; length of a third 

 specimen ^% inch, breadth ^^ inch, height ^ inch. 



Localities. 1. From hills east of Lynyan in gypseous shales, high horizon. 

 Survey-number G xff*- — 2. North-east of Band Vero, from the Operculina beds. 

 Survey-number G ff o- — 3. The same as No. 1. Survey-number G xfy- All are from 

 the Eanikot series of strata. 



Illustrations of the Sjpecies in Plate XVII. 



Fig. 11. The side view: natural size. 



12. From behind : natural size. 



13. Outline of actinal surface : natural size. 



14. The apical system and petals : magnified. 



15. The peristome : magnified. 



k2 



