140 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 
feet to each side within the subanal plastron, but the fact that the 
ambulacral plate No. 10 reaches within the fasciole proves that there 
would have been 4 tube feet enclosed in a later stage. 
It is rather surprising to find the genital pores fully developed 
already at such young age, as it is otherwise a general rule that in 
species attaining a large size (as does I. spatagus, it exceeds a length 
of 100 mm.) genital pores are rather late in appearing. I am then not 
altogether sure that it may not ultimately be found that this young 
specimen (and I have similar specimens of the same size from Mauri- 
tius) represents another species, related to /. spatagus,; also Clark 
(1925) finds such young specimens perplexing. I have, however, no 
specimens of intermediate sizes and must therefore for the present 
content myself with referring these young specimens to Metalia 
spatagus. 
O 
