OF WESTERN SIND. 121 



development of the secondary series of tubercles on the interambulacral plates, these in 

 some examples being confined to the ambital region, whilst in others they extend 

 further towards the peristome or towards the apex, sometimes the inner and sometimes 

 the outer series being the most extensive. 



BemarJcs. This species cannot be mistaken for any of its Indian congeners ; the 

 form of the test, the small and regular tuberculation, and the small peristome readily 

 characterize it. It is distinguished from the Egyptian M. mokattanensis, Cotteau, by 

 the form of the test, which is less turban-shaped and more subconically convex abac- 

 tinally, by the shorter series of secondary tubercles on the interambulacral plates, and 

 by the much more scanty miliary granulation. Micropsis venustula has very close 

 resemblance to Cyphosoma superhum^ Dames, from San Giovanni Ilarione, but differs in 

 the form of the test, and in having the secondary tubercles of the interambulacral plates 

 smaller, less regular, and more confined to the region of the ambitus. The primary 

 tubercles are also smaller. M. venustula resembles C. superbum in having straight uni- 

 serial poriferous zones ; and the differences which separate the two forms generically 

 appear ta be very slight, and may well in such a case suggest doubts as to the propriety 

 of maintaining both the genera as distinct. 



Diameter of the test . 

 Height of the test . 

 Diameter of peristome 



Localities. In the Khirthar series of strata : — i. Twenty-four miles west of Kotri 

 (entering the hills on the road to Bula Khan's Thana). Survey-number ^^. A large 

 series of specimens were obtained from this locality. 



Several examples were also found at 



ii. Gagar Hill, east side of the Surjana range. Survey-number ^^. 



Illustrations of the Species in Plate XXII. 



Fig. 1. Profile view of the test : magnified twice. 



2. Abactinal view of the test : natural size. 



3. Actinal view of the test, showing peristome : natural size. 



4. Abactinal view of the test of a pentagonal variety : natural size. 



5. Apical disk : magnified 7 times. 



6. Ambulacral and interambulacral plates : magnified. 



7. Diagram of the poriferous plates of the ambulacral plate. 



