STUDIES ON TUE DEVELOPMENT OE ECUI INOIDEA. 
291> 
Studies on the Development of Echinoidea. 
II. The Early Larva of Echinocardium cordatum and the 
Result of Crossing' this Species with Echinus esculentus. 
By 
Prof. E. W. yfacl>ri<l(s D.Sr., EL.O., F.K.S., 
Imperial College of Science and Technology, South Kensington. 
With Plates 14 and 15. 
The results recorded in this paper were obtained during- 
two inontlis’ sojourn at the Biological Station of the West of 
Scotland Marine Biological Association at Millport last 
suininer. A preliminary account of the same has already 
been published in the ‘ Proceedings of the Royal Society ’ (16). 
I have to record my t'lanks to Mr. Richard Elmhirst, 
Director of the Station, for the whole-hearted manner in 
which he aided my endeavours, and to Dr. James F. Gemmill, 
\^ice-President of the West of Scotland Marine Biologicjil 
Association, foi' the assistance he rendered me in providing 
me with pure cultuies of diatoms, which were invaluable as 
food for the developing larva;. 'I’o Prof. Graham Kerr, F.R.S., 
and to Di'. Agar, of Glasgow University, my best tlianhs are 
due for the loan of tipparatus from the Zoological department 
of that University. Andhnally, my warmest thanks are due to 
my friend, L. AV. Byrne, Esq., whore-drew my figures forme 
so as to make them suitable for publication. 
The main object of my research was to test the distiibution 
of paternal and maternal characters in the hybrid produced 
by crossing two species, in whose larvae distinctly specific 
characters could be found. 
A great deal of work has been done in crossing distinct 
