OF WESTERN SIND. 313 



Dimensions. The large type specimen measures 185 millim, in its greatest diameter, 

 and 146 millim. in the lesser diameter. It has been crushed laterally. The height of 

 the specimen in its present condition is 98 millim., and, as far as can be judged, the test 

 when perfect was not much higher. 



Localities. In the Gaj series of strata: — i. Mendiari, thirty-five miles north of 

 Karachi. Survey-number G -4^-. 



ii. Eavine on the south-east of Bill, twelve miles north of Shah-beg (the coral 

 zone). Survey-number G -4^^. 



Illustrations of the Species in Plates XLVIII. & XLIX. 



Plate XLVIII. 



Fig. 1. Profile view of the test : natural size. 



2. Actinal view of the test : natural size. 



3. Interradial plates, to show ornamentation : magnified. 



4. Part of the ambulacral area to show the composition of the plates : 



magnified. 

 4 a. Diagrammatic sketch of ambulacral plates, to show the disposition of 

 the ornamentation : magnified. 



Plate XLIX. 



Pig. 1. Fragment of a small test, probably belonging to this species : natural 

 size. 



2. HiPPONOE ANTiQtTA, DtMcan & Sladen. Plate XLIX, Figs. 2-4. 



The test is usually of a medium size, but attains, when well grown, rather large 

 dimensions. Its form appears to be subject to great variation, some specimens being 

 considerably depressed and with the abactinal surface more or less conoid ; whilst 

 others are much higher, decidedly tumid at the sides, and with very little, if any, trace 

 of the conoid form towards the apex. The first-mentioned forms appear to be chiefly 

 large examples, and the more globular tests the smaller ones. It is, however, difficult 

 to indicate with certainty the shape of the test, as all our examples are either crushed 

 or fragmentary ; the species may be said with safety to be extremely variable in many 

 points, like its modern representatives. 



The ambulacral areas, which are flush with the general surface of the test, are of 

 great breadth, their width at the ambitus being only a little less than seven tenths of 

 the width of the interradial areas ; they contract gradually towards the apex, where 

 their outline becomes narrow and pointed. The poriferous zones are straight and of 

 great breadth, being nearly as broad as the width of the interporiferous area ; thus at 

 the ambitus of the largest specimen the breadth of the interradial area measures 

 43 millim., the whole ambulacral area 29 millim., and the poriferous zone 9 millim. 

 The pores form three distinct, vertical, and well-spaced series. The pores of the inner. 



2u 



