OF KACHH AND KATTYWAR. 39 



overhung by the keels. The poriferous zones are wide apart ; and the pairs of pores are 

 at the junction of floor and keel. They are rather distant, oblique, and the pores are 

 separated by a large rectangular or square process. They become very small and 

 lose their process before the ambulacrum is crossed by the fasciole. 



The antero-lateral ambulacra, which are petaloid and small in relation to the size 

 of the test, are placed in moderately deep grooves, which are bounded within by the sharp 

 narrow anterior crests, and posteriorly, near the apex, by the crests of the antero-lateral 

 interradia. The grooves form rather an acute angle with each other, are shallowest 

 at the extremities, and the ambulacra are sinuous, broadest midway, and they are 

 narrow and limited by the fasciole at their distal ends. The interporiferous area is 

 narrow, slightly aslant from before backwards, and it occupies the base of the groove. 

 The poriferous zones are broad, are placed on the slopes of the groove, and the anterior 

 overlaps the posterior at the end of the ambulacrum, the curvature of the anterior 

 being decided there, and the posterior zone not being quite straight but tending to 

 bend backwards. Both zones are curved, and the anterior more so than the posterior ; 

 the anterior is bent near the apex with the concavity forwards and inwards, and there 

 is a greater and outer curve with its concavity backwards and outwards. The 

 curves of the posterior zone are much less than those just noticed, but they are in the 

 same direction. The pairs of pores of one zone do not usually correspond with those 

 of the other ; they are very slightly conjugated ; and a raised narrow costa, rounded and 

 low, is on the broad space between the pairs of pores. The pores are large, comma- 

 shaped, and the outer set are slightly larger than the inner. The outermost and inner- 

 most pores are small. There are 19 or 20 pairs. 



The posterior ambulacra are very small and about one third the length of the 

 antero-lateral pair; they are close, being separated by the posterior narrow keel, 

 elliptical in outline, in shallow grooves ; and there are about ten pairs of pores with a 

 narrow interporiferous area. The pores are smaller than those of the antero-lateral 

 ambulacra. These ambulacra do not reach more than one third of the distance to the 

 posterior margin of the test. 



The anterior interradia are raised into keels on either side of the anterior ambu- 

 lacrum ; they are narrow, very nearly parallel, have a sharp crest which is highest 

 at a point which corresponds with the middle of the antero-lateral ambulacra, and 

 which slopes rapidly behind that point to the apical system. There is a consider- 

 able ornamentation on the surface of the anterior ambulacrum. The ambitus has 

 medium-sized tubercles placed on slightly raised flat scrobicules, which are circular in 

 outline or deformed when close to others ; the bosses are low and rather flattened out 

 and crenulated ; and the mamelons are small and perforate. Where there is any 

 space between the scrobicules there is a fine granulation. Lower than the ambitus 

 and extending below the margin to and on both sides of the peristome are larger 

 tubercles, usually less crowded, with the same structural details on a larger scale. 

 The floor of the ambulacrum is granular; and this condition is seen along the 

 groove to the peristome, a tubercle coming in here and there below the margin. 

 Higher up than the ambitus the tubercles become smaller and smaller and more 



