20 Journal of the Asiatic Society of Bengal. [January, 1910. 



the Gaj beds of Rochro in Kelat (K 10. 630) there is a speci- 

 men of Clypeaster complanatus, Dune, and Slad., which is inter- 

 mediate between the Western Indian and the Burman types in 

 size. One important character of Clypeaster complanatus is 

 that the inner pores are round and the outer pores are oval 

 This distinction is also constant in Mr. Vredenburg's specimen, 

 ».€•! in those parts of the ambula3cral zones which have escaped 

 weathering. But many of the inner pores of the latter speci- 

 men are oval due to weathering, and on close inspection I find 

 that a few of the pores lying in Illb of Dr. Noetling's type are 

 more rounded than oval, showing that those portions of the 

 poriferous zones which are better preserved have retained more 

 of their original form, and that originally the characters of the 

 poriferous zones in Clypeaster complanatus and in C. duncanensis 

 were alike. 



It is clear that the restoration of this species, after 

 Dr. Noetling, is open to modification : and the dimensions of 

 (A) Duncan and Sladen's type of C. complanatus, (B) Mr. 

 Vredenburg's specimen and (C) the Burman type as proposed 

 to be restored by me, are given below: 



Dimensions in millimetres. 



A. B. C. 



Length (a) . . 79 84 110 



Breadth (b) . . 72 79 107 



Base (c) ..47 53 74 



I (d) .. 22 25 33 



II (d) .. 22 25 33 

 HI (e) ..24 27 35 



From the dimensions given above the following ratios are 

 obtained: — 



A. B. C. 



b : a . . 091 094 C97 



c:*> .. 0-65 067 069 



d : c . . 0-51 0-47 0*44 



<*:e .. 0S1 0-92 0-94 



It may be mentioned in this connection that the Geologi- 

 cal burvey collections contain a few duplicates of C. comyla- 

 natus, but most of these are in a fragmentary state, and I could 

 pick out from them only two capable of being measured, and 

 they gave the following results in millimetres : 



(i) (ii ) 



Length (a) .. 62 70 



Breadth (b) .. 55 63 



Base (c) .. % 



41 



