OF WESTEEN SIND. 231 



less pronounced. The odd posterior interradium is distinctly tumid in its median 

 portion. 



The peristome is large, bilabiate, excentric in front, and to a greater degree than 

 the apical system. The anterior margin is the arc of a transverse oval, and the posterior 

 lip is prominent. A wide, but shallow groove is continued from the indentation of the 

 anteal sulcus at the margin up to the peristome, in which the odd anterior ambulacrum 

 is placed ; and there is also a slight troughing near the peristome in the region of the 

 antero-lateral ambulacral areas, the poriferous zones of these latter diverging slightly 

 as they approach the aperture. 



The periproct is very large, subcircular, and occupies the whole of the depth of the 

 small vertical truncation of the posterior extremity. 



The ornamentation is striking and greatly developed. It consists of two sizes of 

 tubercles — one large and the other small. The large primary tubercles, which are per- 

 forate, crenulate, and placed in slightly sunken circular scrobicules, are confined to the 

 abactinal surface, and are all within the bounds of the peripetalous fasciole ; they stand 

 on each of the interradial plates in a regular line parallel with the aboral margin of the 

 plate, and consequently obtusely angulated ; on the plates near the ambitus about a 

 dozen are present, and the number decreases on successive plates as these latter diminish 

 in width as they approach the apex. Each column of the interradia is thus furnished 

 with a series of obtusely angulated lines of primary tubercles. On each plate, beneath 

 the line of large primary tubercles, there are a number of very small tubercles, perforate 

 and in small scrobicules; and the whole of the intermediate parts of the plate are 

 occupied by small, uniform, miliary granulation rather distinctly spaced. At the 

 ambitus and outside the latero-peripetalous fasciole and at the margin of the actinal 

 surface the tuberculation is small and crowded. On the actinal surface proper the 

 primary tubercles are large and well spaced, in slightly sunken scrobicules presenting 

 frequently an upturned disk-margin at one side, the intermediate spaces being orna- 

 mented by very small, uniform, and closely placed miliary granules, of which there are 

 seldom more than one series round the margin of each scrobicule, and with a few 

 additional in the angular interspaces. The posterior ambulacral areas on either side of 

 the actinal plastron are broad, and devoid of large primary tubercles, but closely 

 covered with small granulation. 



There is a very narrow, but distinct, latero-peripetalous fasciole encircling the 

 ambitus, or only very slightly above, and consequently of the widest extent possible on 

 the test, without encroaching on the actinal surface. No trace of a subanal fasciole is 

 discernible ; and furthermore the form of the test does not lead to the suspicion of such 

 a structure having ever existed in the Spatangoid under notice. 



Remarks. This handsome species is readily distinguished from all other Khirthar 

 Spatangoids. Its facies, as determined by the numerous, prominent, and regularly 

 arranged primary tubercles of the abactinal surface and the character of the ambulacral 

 petals, is very unlike that of any Euspatangus ; and on these grounds we have placed it 

 in the genus Macropneustes, notwithstanding the fact that the preservation of our 

 specimen unfortunately does not enable a positive observation to be made as to whether 



2h2 



