[Proc. Eot. Soc. Victoria, 20 (N.S.), Pt. II., 1907.] 



Art XII. — On the occurrence of a Marsitpium in an, 

 Echinoid belonging to the Genus ScuteUina. 



By T. S. hall, I\r.A., 



Melbourne University. 

 [Eead 14tli November, 1907.] 



On a visit to the mouth of the Glenelg River, in the west of 

 Victoria, I collected about twenty-five specimens of ScuteUina. 

 They were found in the ^oft white polyzoal limestone which 

 occupies such a large area of the south-east of South Australia 

 aind the south-western borderland of Victoria. The age of this 

 formation is Banvonian, and may be Eocene. 



On cleaning them with a dental engine a deep depression was 

 displayed in some examples on the actinal surf ace, between the 

 peristome and the anterior maa*gin. The size and shape of the 

 pit varies somewhat in different individuals. It is generally so 

 deep that its upper surface is almost, if not quite, in contact 

 with the abactinal surface of the test. The pit is very shallow 

 near the peristone, but deepens as it runs forward. Its front 

 and lateral walls are vertical. A rounded, but distinct median 

 ridge slightly divides the pit into two halve.-. 



ScuteUina sp., actinal and abactinal views, 



profile, and section tliroug-h marsupium 



and moutli x l^. 



The only suggestion that I can make as to the function of the 

 pit is that it is a marsupium for the protection of the young. 



