OF WESTERN SIND. 



143 



From these observations we may deduce that in the young stages of Amhlypygus 

 subrotundus the test is more elongate, higher, with thicker margins and uniformly 

 convex dorsal surface, and that these modifications produce a stout, elliptical form, very 

 different in general character from that possessed by the mature animal. 



Remarks. This species approaches A. dilatatus, Agassiz, but is distinguished from 

 that form by the general rotundity of the test, its greater height, and the higher 

 and more tumid character of the posterior portion ; the margins are proportionally 

 thicker and more tumid, the poriferous zones appear to be wider, and the actinal 

 portion of the zone is not sunken in a furrow. The periproct differs somewhat in shape, 

 being more pyriform, and is further removed from the posterior margin. The apical 

 system is perhaps rather more excentric. 



Type specimen from locality i. 



Dimensions. 

 (Survey-number ^) :— 



Length of the test 



Breadth of the test 



Height of the test 



From centre of apical disk to posterior extremity 



„ „ „ anterior extremity 



Greatest width of the poriferous zone . . . 

 Width of the interporiferous area at the above pla 



„ „ „ at the margin 



Greatest width of the postero-lateral petal . • 



„ „ antero-lateral petal . . 



„ ,, odd anterior petal . . 



The proportion of length to breadth = 1:0 

 „ „ to height =1:0 



Other specimens measure : — 



ce 



95 

 40 



millim. 



80 



76 



32 



44 



36 

 2-75 

 4-25 

 6 



10-75 

 9-70 

 8-80 



u2 



